@classmethod
def validate(cls, value):
    """Validate that the specified value is a valid enum.

        This method will raise a ValueError if the value is
        not a valid enum.

        :param value: the string value to verify
        """
    if value not in cls.VALUES:
        raise ValueError(
            "Invalid ParameterSource value: '{}'. Valid values are: {}".
            format(value, ','.join(cls.VALUES)))
