code: def is_requirement(line):
      
      return not (
          line == '' or
          line.startswith('-r') or
          line.startswith('#') or
          line.startswith('-e') or
          line.startswith('git+')
      )
docs: Return True if the requirement line is a package requirement;
      that is, it is not blank, a comment, a URL, or an included file.