code: def _prepare_env(self, kwargs):
      
      kwargs = kwargs.copy()
      env = kwargs.pop('env', os.environ).copy()
      env['PATH'] = create_path_env_var(self.extra_paths, env=env, prepend=True)
      return env, kwargs
docs: Returns a modifed copy of kwargs['env'], and a copy of kwargs with 'env' removed.
  
      If there is no 'env' field in the kwargs, os.environ.copy() is used.
      env['PATH'] is set/modified to contain the Node distribution's bin directory at the front.
  
      :param kwargs: The original kwargs.
      :returns: An (env, kwargs) tuple containing the modified env and kwargs copies.
      :rtype: (dict, dict)