code: func (c *chanList) getChan(id uint32) *channel {
  	id -= c.offset
  
  	c.Lock()
  	defer c.Unlock()
  	if id < uint32(len(c.chans)) {
  		return c.chans[id]
  	}
  	return nil
  }
docs: // getChan returns the channel for the given ID.