def get_effective_clock_rate(self):
if self.has_effective_date():<EOL><INDENT>return self._effective_clock_rate<EOL><DEDENT>else:<EOL><INDENT>raise IllegalState()<EOL><DEDENT>
Gets the rate of the clock.

        :return: the rate
        :rtype: ``decimal``
        :raise: ``IllegalState`` -- ``has_effective_date()`` is ``false``

        *compliance: mandatory -- This method must be implemented.*