restore() {
    if (this._stack.length) {
      this._elements = this._stack.pop(); // TODO - use a copy instead
    }
    return this;
  }
/**
   * Sets the current matrix values to the last ones saved on to the stack.
   */
Sets the current matrix values to the last ones saved on to the stack.
Sets the current matrix values to the last ones saved on to the stack .
restore() {
    if (this._stack.length) {
      this._elements = this._stack.pop(); 
    }
    return this;
  }
restore ( ) { if ( this . _stack . length ) { this . _elements = this . _stack . pop ( ) ; } return this ; }
Sets the current matrix values to the last ones saved on to the stack.
Sets the current matrix values to the last ones saved on to the stack .
// TODO - use a copy instead