code: def _connect(self):
          
          if self.connected:
              return
  
          self._connect_broker()
          stack = self._build_stack()
          self._connect_stack(stack)
docs: Establish a connection to the master process's UNIX listener socket,
          constructing a mitogen.master.Router to communicate with the master,
          and a mitogen.parent.Context to represent it.
  
          Depending on the original transport we should emulate, trigger one of
          the _connect_*() service calls defined above to cause the master
          process to establish the real connection on our behalf, or return a
          reference to the existing one.