code: func (s *Session) setSocket(socket *mongoSocket) {
  	info := socket.Acquire()
  	if info.Master {
  		if s.masterSocket != nil {
  			panic("setSocket(master) with existing master socket reserved")
  		}
  		s.masterSocket = socket
  	} else {
  		if s.slaveSocket != nil {
  			panic("setSocket(slave) with existing slave socket reserved")
  		}
  		s.slaveSocket = socket
  	}
  }
docs: // setSocket binds socket to this section.