code: def register(self, addr, ttl):
          
          # a little error checking
          if ttl <= 0:
              raise ValueError("time-to-live must be greater than zero")
  
          # save the BBMD address and time-to-live
          if isinstance(addr, Address):
              self.bbmdAddress = addr
          else:
              self.bbmdAddress = Address(addr)
          self.bbmdTimeToLive = ttl
  
          # install this task to run when it gets a chance
          self.install_task(when=0)
docs: Initiate the process of registering with a BBMD.