code: def send(r, pool=None, stream=False):
      
      if pool is not None:
          return pool.spawn(r.send, stream=stream)
  
      return gevent.spawn(r.send, stream=stream)
docs: Sends the request object using the specified pool. If a pool isn't
      specified this method blocks. Pools are useful because you can specify size
      and can hence limit concurrency.