Rormats the value in various formats

        args:
            method: ['sparql', 'json', 'pyuri']
            dt_format: ['turtle','uri'] used in conjuction with the 'sparql'
                       method

def _format(self, method="sparql", dt_format="turtle"):
        """
        Rormats the value in various formats

        args:
            method: ['sparql', 'json', 'pyuri']
            dt_format: ['turtle','uri'] used in conjuction with the 'sparql'
                       method

        """

        try:
            return __FORMAT_OPTIONS__[method](self, dt_format=dt_format)
        except KeyError:
            raise NotImplementedError("'{}' is not a valid format method"
                                      "".format(method))