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: mkmf.rb
    path of file: ./repos/artichoke/artichoke-backend/vendor/ruby/lib
    
    the code of the file until where you have to start completion: # -*- coding: us-ascii -*-
# frozen-string-literal: false
# module to create Makefile for extension modules
# invoke like:
    
  def have_func(func, headers = nil, opt = "", &b)
    checking_for checking_message(func.funcall_style, headers, opt) do
      if try_func(func, $libs, headers, opt, &b)
        $defs << "-DHAVE_#{func.sans_arguments.tr_cpp}"
        true
      else
        false
      end
    end