def formfield(self, **kwargs):
        """
        :returns: A :class:`~django.forms.FloatField` with ``max_value`` 180 and
            ``min_value`` -180.
        """
        kwargs.update({
            'max_value': 180,
            'min_value': -180,
        })
        return super(LongitudeField, self).formfield(**kwargs)