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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _connection(self):
    '''
    Return a connection from the pool
    '''
    try:
      return self._pool.get(False)
    except Empty:
      args = [
        self._host, self._port, self._keyspace
      ]
      kwargs = {
        'user'              : None,
        'password'          : None,
        'cql_version'       : self._cql_version,
        'compression'       : self._compression,
        'consistency_level' : self._consistency_level,
        'transport'         : self._transport,
      }
      if self._credentials:
        kwargs['user'] = self._credentials['user']
        kwargs['password'] = self._credentials['password']
      return cql.connect(*args, **kwargs)