'Get the number of messages in a queue specified by name.
An internal method to return the number of messages in a queue
specified by name. It returns an integer count of the number
of messages currently in the queue.
:param queue: The name of the queue to be inspected for the number
of messages
:type queue: str
:return the number of messages in the queue specified by name.
:rtype: int'

def _size(self, queue):

    queue_to_check = self._broker.getQueue(queue)
    message_depth = queue_to_check.values[u'msgDepth']
    return message_depth
