code: def prepare_args(config, bootstrap):
      
      config = copy.deepcopy(config)
      environ = dict(copy.deepcopy(os.environ))
  
      data = {'env': bootstrap['env'],
              'pip': pip_cmd(bootstrap['env'], '', return_path=True),
              'requirements': bootstrap['requirements']}
      environ.update(data)
  
      if isinstance(config, string_types):
          return config.format(**environ)
  
      for key, value in iteritems(config):
          if not isinstance(value, string_types):
              continue
          config[key] = value.format(**environ)
  
      return config_to_args(config)
docs: Convert config dict to command line args line.
  
      :param config: Configuration dict.
      :param bootstrap: Bootstrapper configuration dict.