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d��YZd	S(sJMutual exclusion -- for use with module sched

A mutex has two pieces of state -- a 'locked' bit and a queue.
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Otherwise, the queue contains 0 or more (function, argument) pairs
representing functions (or methods) waiting to acquire the lock.
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the first queue entry is removed and its function(argument) pair called,
implying it now has the lock.

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for lock, where a function is called once the lock is aquired.
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