class Gem::OptionParser::AC

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