translate(translate) {
    if (translate === undefined) {
      return new L.Point(this._matrix[4], this._matrix[5]);
    }

    let translateX;
    let translateY;
    if (typeof translate === 'number') {
      translateX = translate;
      translateY = translate;
    } else {
      translateX = translate.x;
      translateY = translate.y;
    }

    return this._add(1, 0, 0, 1, translateX, translateY);
  }
@param {L.Point|Number} translate
@return {L.PM.Matrix|L.Point}