code: def _cork_one(self, s, obj):
          
          rsock, wsock = mitogen.parent.create_socketpair(size=4096)
          mitogen.core.set_cloexec(rsock.fileno())
          mitogen.core.set_cloexec(wsock.fileno())
          mitogen.core.set_block(wsock)  # gevent
          self._rsocks.append(rsock)
          obj.defer(self._do_cork, s, wsock)
docs: Construct a socketpair, saving one side of it, and passing the other to
          `obj` to be written to by one of its threads.