Incorporated R. David Murray's feedback...

   .. method:: acquire(blocking=True, timeout=-1)

      Without any optional argument, this method acquires the lock
      unconditionally, if necessary waiting until it is released by another
      thread (only one thread at a time can acquire a lock).

      If *blocking* is ``False``, the call returns immediately.  If *blocking*
      is ``True``, the lock is acquired unconditionally. In both cases
      the return value indicates whether or not the lock was acquired.

      If the floating-point *timeout* argument is present and positive, it
      specifies the maximum wait time in seconds before returning; the return
      value indicates whether or not the lock was acquired.  A negative
      *timeout* argument specifies an unbounded wait and is the same as not
      specifying a *timeout* and also setting *blocking* to ``True``.  A zero
      *timeout* is the same as not specifying a *timeout* and setting *blocking*
      to ``False``.  You cannot specify a *timeout* if *blocking* is ``False``.

      The return value is ``True`` if the lock is acquired successfully,
      ``False`` if not.