code: def resume_writing(self, exc=None):
          '''Resume writing.
  
          Successive calls to this method will fails unless
          :meth:`pause_writing` is called first.
          '''
          assert self._paused
          self._paused = False
          waiter = self._waiter
          if waiter is not None:
              self._waiter = None
              if not waiter.done():
                  if exc is None:
                      waiter.set_result(None)
                  else:
                      waiter.set_exception(exc)
              self.transport.resume_reading()
          self._write_from_buffer(f resume_writing(self, exc=None):
          '''Resume writing.
  
          Successive calls to this method will fails unless
          :meth:`pause_writing` is called first.
          '''
          assert self._paused
          self._paused = False
          waiter = self._waiter
          if waiter is not None:
              self._waiter = None
              if not waiter.done():
                  if exc is None:
                      waiter.set_result(None)
                  else:
                      waiter.set_exception(exc)
              self.transport.resume_reading()
          self._write_from_buffer()
docs: Resume writing.
  
          Successive calls to this method will fails unless
          :meth:`pause_writing` is called first.