'Thread identifier of this thread or None if it has not been started.
This is a nonzero integer. See the thread.get_ident() function. Thread
identifiers may be recycled when a thread exits and another thread is
created. The identifier is available even after the thread has exited.'

@property
def ident(self):

    assert self.__initialized, 'Thread.__init__()    not    called'
    return self.__ident
