def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def _model_ready_for_local_init(self, sess):
    """Checks if the model is ready to run local_init_op.

    Args:
      sess: A `Session`.

    Returns:
      A tuple (is_ready, msg), where is_ready is True if ready to run
      local_init_op and False otherwise, and msg is `None` if the model is
      ready to run local_init_op, a `String` with the reason why it is not ready
      otherwise.
    """
    return _ready(self._ready_for_local_init_op, sess,
                  "Model not ready for local init")