'Returns the next connection in this pool that is ready to be
reused.  Returns None if there aren\'t any.'

def get(self):

    self.clean()
    for _ in range(len(self.queue)):
        (conn, _) = self.queue.pop(0)
        if self._conn_ready(conn):
            return conn
        else:
            self.put(conn)
    return None
