def get_form_type(self):
        """
        Extract the ``FORM_TYPE`` from the fields.

        :return: ``FORM_TYPE`` value or :data:`None`
        :rtype: :class:`str` or :data:`None`

        Return :data:`None` if no well-formed ``FORM_TYPE`` field is found in
        the list of fields.

        .. versionadded:: 0.8
        """

        for field in self.fields:
            if field.var == "FORM_TYPE" and field.type_ == FieldType.HIDDEN:
                if len(field.values) != 1:
                    return None
                return field.values[0]