The Dynamics of Breathing with Arnold Jacobs and David Cugell, M.D.

By Kevin Kelly

Originally printed in The Instrumentalist, December 1983
Edited by Ed Joffe

At some time, every student of a wind instru­ment is instructed in the “correct” method of breathing. If one studies with two or three different teachers, he/she probably learns two or three different methods, all presumably correct. I studied with six horn teachers and learned five breathing meth­ods, each slightly different and none especially helpful.

The problem is two-fold. First, few teachers ful­ly understand how the body regulates breathing, let alone how the breath is used in wind instru­ment playing. Second, those who have at least a partial understanding teach it in the wrong way, through attention to anatomy. The teacher’s in­complete understanding is conveyed to the stu­dent, who becomes confused, disillusioned, per­haps even immobilized. The standard “art of play­ing” books for each instrument help little, because few are coherent on the subject and even fewer agree with any other text.

 In an attempt to understand this problem, I con­ferred with two noted authorities on the subject of breathing: Dr. David W. Cugell, Bazley Professor of Pulmonary Diseases at the Northwestern University Medical School in Chicago, who also heads the Pulmonary Function Laboratory at North­western Memorial Hospital; and Arnold Jacobs, principal tubist of the Chicago Symphony Orches­tra and a world-renowned teacher, who is sought by students and professionals on all wind instru­ments, primarily for his approach to the psy­chology of breathing. 

Wind instrument players are concerned with the creation and maintenance of a moving column of air, which is the responsibility of the respira­tory muscles alone. Many of the muscles of the ab­domen and chest, and some in the neck, are in­volved in moving air in and out of the lungs. The diaphragm is the one most frequently mentioned in connection with wind instrument playing and the one least understood by wind players. It is popularly considered a main element in the concept of breath “support”–we are often told to support the tone from the diaphragm–as if the diaphragm were active in expiration (blowing air out). It is not.

 “The diaphragm is a muscle of inspiration (tak­ing air in),” Dr. Cugell says. “Located around and above the abdomen (see Example 1), it is unique among the muscles of the body in that it contracts not from one end to the other, as the muscles in your arm, leg, or back would, but in a circular fashion, so that a contraction of the diaphragm will reduce its size while flattening it out. The dia­phragm is connected to the lower ribs in such a manner that when it contracts it moves down­ward. It’s one muscle, but like all muscles it’s made up of multiple fibers that contract synchro­nously. When it contracts, the effect is to push it downward.

“The active part of breathing is the inspiratory portion. In order to move air into the chest and ex­pand the lungs, an active muscle effort is required, and that means contraction of the diaphragm. Now you can produce a little bit of breathing by contracting other muscles, such as the strap mus­cles in the neck. You see someone complete a hun­dred-yard dash, they’re gasping and tugging with their neck muscles as well as with their dia­phragm, but that’s the agonal gasp of the subject who is in extremes of physical activity, which is not the case when you’re playing a musical instru­ment. You may need to breathe in a hurry, or you may need a big breath, but coordinated and planned breathing is not assisted by contracting some of these other muscles. They contribute relatively little in comparison with what a healthy diaphragm can do.” 

Cugell points out that the diaphragm functions only to assist taking the air in. “It’s the other mus­cles, particularly in the chest area and the ab­domen, that we use to exhale and that collectively develop the air pressure you need to play. 

“A man in England did a nice little study in which he had a number of trained singers stand in front of a fluoroscope (an instrument used to ex­amine the interior of a body) and told them to sus­tain a note with the breath coming from the dia­phragm in whatever manner they were trained. Then he repeated the process and had the singers breathe in a manner which was quite incorrect, without using the diaphragm in the way in which they had been instructed. The fluoroscope showed no difference whatsoever in the activity of the dia­phragm under these two circumstances. This is really not surprising, because the diaphragm ac­counts for 90% of all breathing and you cannot control or change the proportion of your breath­ing that is contributed by it or by a few other muscles whose contribution is relatively small. 

“Now what I suspect is happening is that when someone sustains a high C in a proper way ‘using the diaphragm’ as opposed to someone who does it improperly, it has not really anything to do with the diaphragm. It has to do with how the person contracts other muscles in the abdomen and chest. This information has been transferred in the lingo of singers and wind instrument play­ers to assume that this exhaling is accomplished with the diaphragm, when in fact it is done by con­tracting other muscles. 

There are two overlapping layers of muscles be­tween the ribs, called the intercostal muscles. Some contract during inspiration and some con­tract during expiration. If I inhale in a hurry and I want to stop at a certain point, before I actually stop, the muscles which move the chest in the op­posite direction begin to work. It is this interplay of the muscles that move things in opposite direc­tions which provides the fine control.” The amount of control the wind instrument player has over this procedure is limited by what is called the pressure-volume diagram of the chest (Example 2), which says that greater pressure is required to move air at volumes below the resting lung volume than at volumes above the resting point.

As Cugell explained it, “In the lung the pres­sure-volume relationship is linear over the mid­range. That is, I get equal volume increments for equal pressure increments. Once I reach the elas­tic limit, no matter how much pressure I apply, I don’t get any more volume. 

“With no conscious effort to facilitate things, the pressure is greatest when the lungs are largest. Similarly, when the lungs are largest, the con­scious contraction of the muscles produces the highest pressures. Active expiratory effort is, of course, needed whenever the required mouth pressure for the instrument is higher than the re­laxation pressure at the prevailing lung volume. As the lungs get smaller, they are no longer going to contract and generate pressures on their own. You have to do it by squeezing with the muscles. 

“For example, if you inflate the lungs to their ab­solute maximum and then play a high C on the trumpet at maximum volume, you haven’t used much air, but the volume of air in the chest is re­duced considerably because you’ve had to squeeze so much. You compress the air in the chest just as much as the air in the mouth. Whether you have an instrument that has a low pressure, for which you’re going to need a high air flow to get a large sound volume, or you’re playing an instrument that has a low flow at enormous pressure (one that uses a small mouthpiece) the effort required of the player is essentially the same. In other words, you’ve got to squeeze with the muscles to generate either a high flow or a high pressure.

“The vast difference is that if you don’t need much pressure you can play with the entire usable portion of the lung volume. However, if you need a lot of pressure, you can only use a small portion of the lung capacity because when the lungs are par­tially empty it’s not possible to generate the pres­sure, as shown in example 2. You can generate the maximum pressures when the lungs are full, and you want to do that to play a loud, high note; but after you’ve exhaled some air the lungs are smaller and then it’s not possible to sustain as high a pressure. So, there is a limited period of time when a player has both the volume and the pressures to produce the sound. On the other hand, the time during which an oboist can sustain a note is not limited so much by the air pressure and air flow requirements of the instrument as by his breath-holding time. If you don’t need much pressure and you don’t need much flow, then you’ve got all day; but there’s only so long you can hold on before you’ve got to breathe again.” 

The point that Cugell insisted upon throughout our discussions is that, given all the facts of breathing anatomy, each player will discover the practical applications for himself. “I’m a firm be­liever in the capacity of the organism to minimize the burden of the work it has to achieve. In other words, there are studies that show whatever breathing pattern people assume generally repre­sents the minimum amount of work that is re­quired to produce the necessary amount of breath­ing.

 “For example, people with a certain kind of lung disease breathe with a large breath relatively slowly when making objective measurements of the work of breathing. By that I mean the pressure, the volume, the physical parameters of work. You will find that if you change their breathing so that they are breathing with a smaller volume more frequently, the work re­quired is larger. A patient who has the kind of lung disease that makes the lung stiff may adopt a breathing pattern of panting. He does that be­cause it takes a lot of work to distend a stiff lung. The patient can breathe the necessary amount if he breathes quickly and at small volumes. If you tell him, ‘Gee, you’re breathing all wrong. Try tak­ing a big breath and breathe less frequently, you’ll get the same amount of breathing for it,’ he’ll say, ‘Well I tried it and I didn’t like it,’ because he had to work so hard to expand the stiff lung.

“My point is that the compensatory pattern of breathing that people spontaneously adopt will represent the minimum work that is required, and it is probably incorrect to impose a different pat­tern. I think a person playing a wind instrument fits into the same category. If he’s got to grab a breath between two passages, he’s going to do it in a way that’s best for him; I doubt that there would be any purpose in imposing a different pattern. If the player did it once and ran out of air, the next time the player going to breathe a little more because they know they have to.” 

Furthermore, the particular breathing pattern a person adopts is no indication of his quality as a wind instrument player. Cugell says, “If you com­pare the breathing patterns of you and me or any­body else, they would all be different, but there would be no way to categorize that as saying ‘nor­mal’ or ‘abnormal’ or ‘this one’s old’ or ‘this one’s young.’ There’s nothing characteristic about breathing that can be defined as representing gra­dations of normality. That being the case, it’s not surprising that if four people play the same music, they’re going to breathe a little differently, be­cause they breathe differently when they’re not playing music.”

 He referred to the Nature article where Bou­huys tested four flutists playing Debussy’s Syrinx. One of these men was first chair in the Concertge­bouw Orchestra of Amsterdam, one was a good amateur, and two were young professionals. Re­cordings from a pneumograph (an instrument de­signed to measure chest movement during respira­tion) showed four slightly divergent readings with­in the same general pattern, with slight tempo fluctuations. With the exception of one man, who had a slightly smaller lung capacity and took one extra breath, the performers adhered to the phrase-breath markings in the music. This test showed to what extent the music determines a player’s breathing pattern. “So, if we subscribe to the concept, with respect to instrument playing, that we will spontaneously assume the most effi­cient and effective pattern,” says Cugell, “then it certainly makes good sense not to concern your­self with it so you can concentrate on all the other aspects of your playing.” 

Anatomy and Psychology

Arnold Jacobs bases his teaching on all these other aspects of sound and phrase – the “prod­ucts” of music. He makes the distinction between anatomy and function through what he calls the “computer activity of the brain,” separate from the “thinking part of the brain.” 

“When you go to the product of whatever you’re trying to accomplish, you’ll find the physical ac­tion required to do it is based in the computer ac­tivity of the brain. In other words, the conscious levels of the brain, where volitional thought takes place, handle the product. Another level of the brain, the thinking part, will handle motor im­pulses carried by nerves throughout the body. The firing up of the systems is handled at subcon­scious levels, just like the ability to walk or to talk or to run. The muscle activity will result from what you’re trying to accomplish. With all ma­chines there is a set’ of controls, like an automo­bile, which has complex machinery under the hood but simple controls in the driver’s compart­ment. There’s nothing as complex on this planet as the human being; but man has magnificent con­trols, and he goes through this control system. By this I mean that there are divisions in the brain that are going to control all sorts of physical functions – cutting up food, bringing it to the mouth and chewing it, handling the body for sleep at night, or even going insane. The thinking part of the brain is free to cope with life around us, it does not have to cope with life within us. It’s with the thinking part of the brain that we begin to estab­lish what we want in the way of product. 

“This, of course, is what players are up against; in music, so often a teacher makes the mistake of altering the machine activity rather than altering the product or what he wants accomplished. The instructor is giving machine methods of how to do it, and people can’t work that way. None of us can. We have to look for the easy answer all the time. It is so simple. If you want a lot of breath, just take a lot of air. Don’t worry about where it goes. If you want to blow, just blow. With students a teacher should always try for the simple answers that bring about proper motor response. That idea be­longs not in the realm of anatomy but in psychol­ogy.”

 The answer that Jacobs introduces students to is what he calls the “phenomenon of wind”–the idea of air blowing out through the instrument to prevent pressures from building up inside the lungs. Most students who come to Jacob have ac­quired the habits of thinking about air pressure in­stead of air in motion. Because these habits are difficult to break, he uses psychology to create new habits, to get students to use their muscles for the proper function. 

The respiratory muscles are involved in three ways. One is respiration, the single complete act of breathing in and out. The second has to do with pelvic pressures when the Upper end of the airway is closed, forcing pressure downward for such events as defecation and childbirth. The third has to do with the isometrics of physical function, the kind of static muscle tightening involved in weightlifting and wrestling.

 “A musician has to make sure that he is using the right approach when playing an instrument,” Ja­cobs says. “He doesn’t want the one that immo­bilizes, he doesn’t want the one that creates great isometric contractions that have no movement potential. Because a continuous flow of air re­quires movement, the player should go to res­piration. 

“The human brain is responsible for conditioned responses to stimuli or reflex responses to stimuli in everybody, musicians or non-musicians. These are non-respiratory functions. In respiration a bellows action occurs in the muscles. We take air in and we blow air out by the phenomena of en­largement and reduction. It becomes simple when you think of movements of air. Whether it’s from the diaphragm descending or the rib cage ascend­ing, there has to be enlargement to lower air pressure internally below atmospheric pressure so air will move into the lungs. The same thing happens as you reduce the size– the air pressure increases as you move out. That’s how we blow; it’s how we breathe.

Move Air As Wind

“The psychology of blowing is always to blow outward, to work with wind rather than air pres­sure. The psychology of it is important. Take your hand, hold it at a distance and blow onto it. Now where the air lands is the area to concentrate on. Some teachers will have the player blow through the instrument or through the far wall. It doesn’t matter what the technique is to motivate a stu­dent; the psychology of it is to move air as wind, not air pressure. 

“With wind there is always air pressure. With air pressure, there is not always wind. If you just concentrate on the air pressure-which can hap­ pen in any body cavity–the danger is that you may have stimulated the Valsalva maneuver (in which you try to breathe out with your mouth and nose shut) or the pelvic pressure syndrome, or the isometrics, which do not involve movements of air.

 “But an instructor is never going to get this idea across by telling students to push with this muscle or that muscle. I get them to blow. Away from the instrument I let them observe their body. I use special equipment, or I may have students blow up balloons or blow out matches, and then show how quantities can be taken from any part of the thorax (the body area between the neck and the ab­domen). In other words, we go through a certain amount of perspective training away from music to become acquainted with the body, so that the studies of air in life are involved.” 

The confusion of many teachers about both the role of the diaphragm and the idea of abdominal “support” of air is largely responsible for many students’ preoccupation with the kind of pres­sures resulting from misdirected muscular ten­sions.  Jacobs continues: “First of all, the term ‘support’ raises questions in itself. Many people make the mistake of assum­ing the muscle contraction is what gives support. The blowing of the breath should be the support, not tension in the muscles of the body, but the movement of air as required by the embouchure or the reed.

 “You go into the mechanics of movement and confusion arises; it’s a cause-and-effect relation­ship. When a player blows, the body undergoes certain changes. There will be increasing palpable tensions that can be felt just by touching a person. Toward the end of a breath, there will be a certain number of fibers that are stimulated. There will be increasing motor activity in order to get the air out, and this varies according to the length of the phrase and the amount of air in the lungs original­ly; but ‘support’ is never ‘tight muscles,’ whether you’re silent or blowing, or in a diminuendo or crescendo. In other words, it’s simply a static, con­stant, isometric type of contraction that so many people call support. This is not support at all. 

“I can explain it from different points of view. Do it this way: your diaphragm is like the floor, a movable partition between the thoracic and the abdominal cavities. Now if you were to build up considerable air pressure with a loose abdomen and a loose diaphragm, the air would simply move the floor downward. Instead of air coming out, as the player builds pressure it would simply lower the floor. So, by thinking of support as something that will hold the diaphragm in the upper position, you could conceivably see abdominal tension as building pressure beneath the floor. You keep that in a fixed position while building up high pressure through the rib activity to have expulsion of breath based on this pressure. I can’t conceive of it this way, but I know that many teachers think this way. This is not, to me, support.

 “Support is always a reduction phenomenon. Wherever the player is going to build pressure, ac­cording to Boyle’s Law, he is going to have a re­duced chamber. Now the chamber can be reduced anywhere it is enlarged. It gets bigger when you take air in, it gets smaller when you move air out. When you blow, the brain will deactivate the dia­phragm, normally. Expiratory function will nor­mally deactivate inspiratory function. If you are using air to create pelvic pressures, the dia­phragm will not deactivate -it will remain stimu­lated. Abdominal muscles that would normally be expiratory will start contracting, and there will be a closure at the throat or the tongue or the lips which causes the air pressure to bear down on a downward-contracting diaphragm to increase the pelvic pressure for expulsion of fecal matter. Of course, to bypass this we have to have a blowing phenomenon that is different. You see, you have to form a new habit, and a new habit does not come right away. A new habit takes time to reach the subconscious level.”

 Jacobs uses a wide variety of non-musical exer­cises to get players to feel and hear the difference between blowing air out freely and blowing out in a choked manner that results in tight chest and ab­dominal muscles. For example, blow onto the back of the hand using a tight hissing sound through your teeth, as loud as possible. You will feel very little air. By blowing out freely onto the hand, you feel a considerable amount of air under low pres­sure. The hiss is under high pressure, but there is little quantity. By closing the lips in the midst of the hiss and then releasing the sound explosively, you will have felt considerable pressure behind the lips and also behind the tongue. As soon as you open the lips, you have an immediate shortage of air.

 “We see these closures in students all the time,” Jacobs says, “coming from a sibilant ‘s’ (the hissing sound) or at the back of the tongue, and even some where the larynx and epiglottis start to come to­gether. If I have a student whose tongue is block­ing the air, allowing very little air movement but at high pressure, I immediately encourage using the open vowel form such as ‘oh’ or ‘ah.’ All through life you have language; language involves the tongue. Over the years you have built up reflex response for shape that is very powerful. You hear a trumpet or a bassoon, but it sounds like a singer with a voice like that singing ‘oh.’ Listen for that sound and the tongue shape is correct. This per­tains to any need to open up the airway.” 

Following one of Jacobs’ recent master classes at Northwestern University, a woman asked how to help a bassoon student who lets the air get “like a brick wall”–constricted and tense–which ap­parently resulted in quite a horrible sound. 

“First of all, get her away from the bas­soon. You don’t have to use the reed; just put something in her mouth. Have the student start blowing or start blowing against something in order to see that the air will do something where it lands. The importance of this approach is not to correct what’s wrong, but to establish what should be right.

 “I would give her a couple of straws and have her blow at the pages of a book and watch what happens on the other side. Have her blow at some matches or blow up a weak balloon, but always with the thought of becoming acquainted with air, rather than air pressure. Studying childbirth and coughing gives the picture of what air pressure will do. However, when you study a burn and cool it by blowing on the hand, or when you’re doing what I used to do, blow peas at people with a pea shooter, then you get a different picture of what air will do.” 

The woman pointed out that this particular stu­dent was a singer who had played the bassoon for only a year. “Don’t singers have to use a lot of air?” she asked. 

“No, it’s just the opposite,” Jacobs said. “Singers use less air than anybody. Their reed is at the throat, and as a result they have to keep a fairly sizable pressure at the laryngeal region. The stu­dent is using the technique of singing on the bas­soon. Now compared to singing, bassoon playing will seem like a large volume of air is in transit. It’s important to recognize that she has habits already formed. 

“Start mechanical movements without the in­strument so the student experiences change in the abdominal-diaphragmatic relationship. Deliber­ately have her create massive motions in the ab­dominal region, sucking the belly in, forcing it out, pushing it up and down -this is the region where she’s been stabilized. Now deliberately destabilize it. Start the muscle activity of change in front of a mirror so the senses work together to strengthen each other. Don’t tie it into music, though, or else she’ll have to fight her own habits.

“Then tie in the movements of air by using mo­tion–every day blow out matches, taking in lots of air and enlarging. Allow a few weeks, where she has to be practicing this every day. In the ab­dominal region where the student was stable, she will begin to establish motility of function. It has to be recognized in this manner before you apply it to the bassoon. Then you do it with just some reed squawks, but with exaggeration.

 “Exaggeration is one of the important tools. Do­ing things just right is not what you want. The recognition is not there. So, you over-change. You’re not doing it with the music, so there’s no damage. Then when you get to the bassoon, you don’t worry about the body change, but you go to the study of air. It is natural for the lungs to get smaller as you use up air. The bassoon student has made it unna­tural. As a teacher, you go through a program to get her back to what is natural. As soon as this process starts, she begins to use air as wind to deactivate the diaphragm. There can be no stiff­ness in the anterior abdominal wall without the antagonist, which is the diaphragm. The brain will deactivate this action, and as the diaphragm comes up, you’ll find the student is able to blow against the reed, where the wind belongs. If you tell her to do these things based on intelligence, she will understand, but she can’t communicate it to her body. The wind becomes the body’s signal for change. 

It’s the Tone

 “But wind is finally only a minor part. Tone pro­duction is the major. You use the wind as fuel. With a wind instrument, the horn resonates sound waves; it’s reacting to sound and amplifying it ac­cording to acoustical properties. Our air isn’t used to fill an instrument. It’s used by the embouchure as energy, so the lips vibrate. 

“So, players certainly shouldn’t worry about the air, but about the quality of tone. When you get the tone, you will have all the requirements of tone at the subconscious levels. The blowing is an incidental part; the tone doesn’t exist without the blowing, but the blowing can exist without the tone. As an artist you go for the product – the product is sound and phrase and all the emotions in music–you use thought processes that stimu­late motor function, but you don’t worry about the function. You worry about the sound. You will use the breath as needed. You will do it primarily without awareness of air. The air should be used freely – waste it, do anything you want. A player’s awareness is of the communication of sound to whoever he is talking to. 

“This is true of any wind instrument. You teach expertise in phrase and the study of dynamics. As the sound production becomes more efficient, which it will, you’ll find that you use the breath with greater and greater ease. I’m an old man, but I can still function quite well in playing a brass in­strument, because my lips respond quite readily to my thoughts. Moving air under pressure is re­quired for my lips to vibrate, but those lips are not trying to resist the air. They’re trying to vibrate based on the thoughts coming from my brain in terms of sounds.”

There are, of course, many ways students and professionals have of inhibiting their ability to ex­press sound freely. Probably the most common is poor posture. “Posture is very important,” Jacobs acknowledges. “We’re structured so that the max­imal use of air comes in the standing posture, as if you would run or fight for your life. Standing of­fers the greatest ability to move large volumes of air in and out of the lungs. The closer you get to the supine, the poorer it becomes.

 “If you think of the respiratory system, it should be thought of not as one bellows, but as a series of segmented bellows, depending on your posture. When lying on your back on the floor, you’ll find there is little ability to use chest breathing. You will have a marvelous use of diaphragmatic breathing, which is more than enough to sustain life; but the diaphragm isolated from the rest of the rib cage provides a rather small breath. There is no such thing as a full breath without the use of the sternum (the compound ventral bone and car­tilage that supports the ribs). If I lean back on the chair and reach over my head, the motion pulls the rib cage up, which is already in the expanded posi­tion. That means I can’t use it for breathing in or out. If I bend forward over my belly, pressure in the abdominal region under the diaphragm is such that I have great difficulty using diaphragmatic function.

 “If you need large volumes of air, you will use the entire respiratory system. If you’re playing an instrument that doesn’t require much air, you’re never going to use a full breath; however, you should be able to. Performers have to take suffi­cient air in to be able to complete phrases. This in­volves taking in quantities of air based on judg­ments of how much air will be left at the end of a phrase.

 “Standing while seated is the best posture be­cause players have the greatest ability to move air in and out of the lungs. However, if you are breathing with comfort, the posture doesn’t have to be that way. As long as you are in the upright position, you should have more than enough air. If you’re a large person with large lung reserves, pos­ture is not that important; however, people who have small lung volumes must stay upright and make use of whatever nature gave them.” (We come back to the point that Cugell made earlier: the body will adopt the most comfortable and ef­fective means of performing whatever task it is given to do.) 

“In this art form,” Jacobs concludes, “we are dealing in sound. Respiration is made too much of. We need sufficient quantities of fuel that we can use easily. As I say, waste it, it’s free–but don’t make a big deal out of it. We don’t start anything with skill; skill is developed over a period of time in spite of yourself. We have to recognize what we’re trying to accomplish; the orders that come from the various parts of the brain must be based on the sound of the instrument. We have to make sure that we don’t take the level of the brain at which we have volitional thought and try to take charge of the human machine through its indi­vidual components. We can’t handle it. You’ve got to get out of the way and allow your body to func­tion for you. The point is to try to sound great when you play.” 

Arnold Jacobs was principal tubist of the Chicago Symphony Orchestra, from 1944-1988. At the age of 15, he became a stu­dent at Philadelphia’s Curtis Institute of Music and went on to play with the Indianapolis and Pittsburgh Sym­phonies. He toured with Leopold Stokowski and the All-American Youth Orchestra before joining the Chicago Symphony Orchestra. Arnold Jacobs died in 1998.

David W. Cugell, M.D. was head of the pulmonary function laboratory at North­western Memorial hospital in Chicago and had been a member of the faculty of Feinberg School of Medicine School for 58 years–the longest tenured faculty member in the history of Northwestern University. A graduate of Yale University and the State University of New York School of Medicine in Brooklyn, Cugell was president of the Chicago Lung Association. A musician as well as a physician, he played clarinet and saxophone. Dr. Cugell died in 2016 at the age of 93.

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