# File lib/brb/tunnel/shared.rb, line 110
      def treat_callback_return(ret, key, nb_out)

        if b = get_callback(key, nb_out)
          EM.defer do
            # With arity, handle multiple block arguments or no arguments
            b.arity == 1 ? b.call(ret) : (b.arity == 0 ? b.call : b.call(*ret)) 
          end

          # A callback has been found and called, return true
          return true
        end
        
        # No callback, do nothing
        return nil
      end