code: def virtualenv_requirements(version_info=sys.version_info):
      
      if version_info < (2, 5):
          # 'virtualenv' release 1.8 dropped Python 2.4.x compatibility.
          yield requirement_spec("virtualenv",
              ("<", lowest_version_string_with_prefix("1.8")))
      elif version_info < (2, 6):
          # 'virtualenv' release 1.10 dropped Python 2.5.x compatibility.
          yield requirement_spec("virtualenv",
              ("<", lowest_version_string_with_prefix("1.10")))
      else:
          yield requirement_spec("virtualenv")
docs: Generate Python version specific virtualenv package requirements.
  
      The requirements are returned as setuptools/pip compatible requirement
      specification strings.