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: mdoc2man.rb
    path of file: ./repos/artichoke/artichoke-backend/vendor/ruby/tool
    
    the code of the file until where you have to start completion: #!/usr/bin/env ruby
###
### mdoc2man - mdoc to man converter
###
### Quick usage:  mdoc2man.rb < mdoc_manpage.8 > man_manpage.8
###
### Ported from Perl by Akinori MUSHA.
###
###  Copyright (c) 2001 University of Illinois Board of Trustees
###  Copy
    
  def parse_macro(line)
    words = line.split
    retval = ''

    quote = []
    dl = false

    while word = words.shift
      case word
      when RE_PUNCT
        next retval << word if word == ':'
	while q = quote.pop
	  case q
	  when OPTION
	    retval << ']'
	  when PAREN
	    retval << ')'
	  when ANGLE
	    retval << '>'
	  end