Return the value cast to a float.

        :param value: The number.
        :return: The number as a float.

def fn_float(self, value):
        """
        Return the value cast to a float.

        :param value: The number.
        :return: The number as a float.
        """

        if is_ndarray(value) or isinstance(value, (list, tuple)):
            return self._to_ndarray(value).astype('float')
        else:
            return float(value)