_transform (elem) {
    let result
    for (let i = 0; i < this._transforms.length; i++) {
      result = this._transforms[i](elem)
      if (result !== null) break
    }
    return result || elem
  }
/**
   * Applies all transforms to an element, stopping when a transform returns a
   * non-null value.
   * @param {*} elem Any element to be transformed
   * @returns {*} The transformed element, or the original element if no
   *   transform modified it.
   * @private
   */
Applies all transforms to an element, stopping when a transform returns a
non-null value.
@param {*} elem Any element to be transformed
@returns {*} The transformed element, or the original element if no
transform modified it.
@private
Applies all transforms to an element stopping when a transform returns a non - null value . @param { * } elem Any element to be transformed @returns { * } The transformed element or the original element if no transform modified it . @private
_transform (elem) {
    let result
    for (let i = 0; i < this._transforms.length; i++) {
      result = this._transforms[i](elem)
      if (result !== null) break
    }
    return result || elem
  }
_transform ( elem ) { let result for ( let i = 0 ; i < this . _transforms . length ; i ++ ) { result = this . _transforms [ i ] ( elem ) if ( result !== null ) break } return result || elem }
Applies all transforms to an element, stopping when a transform returns a
 non-null value.
Applies all transforms to an element stopping when a transform returns a non - null value .