Returns the HREF of a dynamic choice parameter.
        Throws an error if this is not a choice parameter.

def get_choice_href(self):
        """
        Returns the HREF of a dynamic choice parameter.
        Throws an error if this is not a choice parameter.
        """
        if 'choiceInfo' not in self.dto[self.name]:
            raise GPException('not a choice parameter')

        return self.dto[self.name]['choiceInfo']['href']