whole_func_string: function rename(obj) {
    return rename_(function(parsedPath) {
      return {
        extname: obj.extname || parsedPath.extname,
        dirname: (obj.dirnamePrefix || '') + parsedPath.dirname,
        basename: parsedPath.basename
      };
    });
  }
func_code_string: function rename(obj) {
    return rename_(function(parsedPath) {
      return {
        extname: obj.extname || parsedPath.extname,
        dirname: (obj.dirnamePrefix || '') + parsedPath.dirname,
        basename: parsedPath.basename
      };
    });
  }
func_documentation_string: A wrapper around gulp-rename to support `dirnamePrefix`.