code: func (c *Connection) NotifyBlocked(receiver chan Blocking) chan Blocking {
  	c.m.Lock()
  	defer c.m.Unlock()
  
  	if c.noNotify {
  		close(receiver)
  	} else {
  		c.blocks = append(c.blocks, receiver)
  	}
  
  	return receiver
  }
docs: /*
  NotifyBlocked registers a listener for RabbitMQ specific TCP flow control
  method extensions connection.blocked and connection.unblocked.  Flow control is
  active with a reason when Blocking.Blocked is true.  When a Connection is
  blocked, all methods will block across all connections until server resources
  become free again.
  
  This optional extension is supported by the server when the
  "connection.blocked" server capability key is true.
  
  */