<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_pause_time(self, speed=ETHER_SPEED_MBIT_1000):
 """ get pause time for given link speed in seconds :param speed: select link speed to get the pause time for, must be ETHER_SPEED_MBIT_[10,100,1000] # noqa: E501 :return: pause time in seconds :raises MACControlInvalidSpeedException: on invalid speed selector """


        try:
            return self.pause_time * {
                ETHER_SPEED_MBIT_10: (0.0000001 * 512),
                ETHER_SPEED_MBIT_100: (0.00000001 * 512),
                ETHER_SPEED_MBIT_1000: (0.000000001 * 512 * 2)
            }[speed]
        except KeyError:
            raise MACControlInvalidSpeedException('Invalid speed selector given. '  # noqa: E501
                                                  'Must be one of ETHER_SPEED_MBIT_[10,100,1000]')