Return a generator over the (value, label) pairs, where value
        is a string associated with each choice. This convenience method
        is useful to populate, for instance, a form select field.

        :param valuegetter: Can be a callable or a string. In the former case, it must
            be a one-argument callable which returns the value of a
            choice. In the latter case, the string specifies the name
            of an attribute of the choice objects. Defaults to `str()`
            or `unicode()`.

def options(self, valuegetter=text_type):
        """Return a generator over the (value, label) pairs, where value
        is a string associated with each choice. This convenience method
        is useful to populate, for instance, a form select field.

        :param valuegetter: Can be a callable or a string. In the former case, it must
            be a one-argument callable which returns the value of a
            choice. In the latter case, the string specifies the name
            of an attribute of the choice objects. Defaults to `str()`
            or `unicode()`.
        """
        valuegetter = valuegetter if callable(valuegetter) else attrgetter(valuegetter)
        pairs = zip_longest(self.choices, self.labels, fillvalue='')

        return ((valuegetter(choice), label) for choice, label in pairs)