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

        return: (decimal) - the rate
        raise:  IllegalState - ``has_effective_date()`` is ``false``
        *compliance: mandatory -- This method must be implemented.*