You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ac.rb
    path of file: ./repos/ruby-packer/ruby/lib/optparse
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
require 'optparse'

clas
    
  def _ac_arg_enable(prefix, name, help_string, block)
    _check_ac_args(name, block)

    sdesc = []
    ldesc = ["--#{prefix}-#{name}"]
    desc = [help_string]
    q = name.downcase
    ac_block = proc {|val| block.call(ARG_CONV.call(val))}
    enable = Switch::PlacedArgument.new(nil, ARG_CONV, sdesc, ldesc, nil, desc, ac_block)
    disable = Switch::NoArgument.new(nil, proc {false}, sdesc, ldesc, nil, desc, ac_block)
    top.append(enable, [], ["enable-" + q], disable, ['disable-' + q])
    enable
  end