Extracts a value for the field from an XML-RPC response.

def convert_to_python(self, xmlrpc=None):
        """
        Extracts a value for the field from an XML-RPC response.
        """
        if xmlrpc:
            return xmlrpc.get(self.name, self.default)
        elif self.default:
            return self.default
        else:
            return None