Thanks for the patch.

First, you don't need to support str, since sockets only accept binary strings (not unicode).

Second, I think it's simpler and more generic to do something like:

  try:
      self.sock.sendall(data)
  except TypeError:
      try:
          it = iter(data)
      except TypeError:
          raise TypeError("data should be a bytes-like object or "
              "an iterable, got %r" % type(it))
      for d in t:
          self.sock.sendall(d)