Class Queue implements queue objects and has the methods
described below. This class can be derived from in order to implement
other queue organizations (e.g. stack) but the inheritable interface
is not described here. See the source code for details. The public
methods are:
Put item into the queue. If optional argument block is 1
(the default), block if necessary until a free slot is available.
Otherwise (block is 0), put item on the queue if a free
slot is immediately available, else raise the Full
exception.
Remove and return an item from the queue. If optional argument
block is 1 (the default), block if necessary until an item is
available. Otherwise (block is 0), return an item if one is
immediately available, else raise the
Empty exception.
