code: def flush(self):
          
  
          # Ensure we're not closed.
          self.require_not_closed()
  
          # Pull out the accumulated chunk.
          chunk = self._stream.getvalue()
          self._stream.truncate(0)
          self._stream.seek(0)
  
          # Append the chunk to the body.
          self.body = chunk if (self._body is None) else (self._body + chunk)
  
          if self.asynchronous:
              # We are now streaming because we're asynchronous.
              self.streaming = True
docs: Flush the write buffers of the stream.
  
          This results in writing the current contents of the write buffer to
          the transport layer, initiating the HTTP/1.1 response. This initiates
          a streaming response. If the `Content-Length` header is not given
          then the chunked `Transfer-Encoding` is applied.