def each_coupling_reverse(port)
      return enum_for(:each_coupling_reverse) unless block_given?
      each_input_coupling_reverse(port, &block)
      each_internal_coupling_reverse(port, &block)
      each_output_coupling_reverse(port, &block)
    end
def each_coupling_reverse(port)
      return enum_for(:each_coupling_reverse) unless block_given?
      each_input_coupling_reverse(port, &block)
      each_internal_coupling_reverse(port, &block)
      each_output_coupling_reverse(port, &block)
    end
TODO doc