class RuboCop::Cop::Performance::Casecmp

def on_send(node)
  return unless downcase_eq(node) || eq_downcase(node)
  return unless (parts = take_method_apart(node))
  _receiver, method, arg, variable = parts
  good_method = build_good_method(method, arg, variable)
  message = format(MSG, good: good_method, bad: node.source)
  add_offense(node, message: message) do |corrector|
    autocorrect(corrector, node, good_method)
  end
end