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 update_state(self, y_true, y_pred, sample_weight=None):
    sample_weight = _apply_mask(y_true, sample_weight, self._masked_tokens,
                                self._dtype)
    num_classes = tf.shape(y_pred)[-1]
    y_true = tf.reshape(y_true, [-1])
    y_pred = tf.reshape(y_pred, [-1, num_classes])
    sample_weight = tf.reshape(sample_weight, [-1])
    super().update_state(y_true, y_pred, sample_weight)