<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def authy(self):
 """ Access the Authy Twilio Domain :returns: Authy Twilio Domain :rtype: twilio.rest.authy.Authy """

        if self._authy is None:
            from twilio.rest.authy import Authy
            self._authy = Authy(self)
        return self._authy