protected function addValidAttributes( $attrs ) {
        foreach( $attrs as $attr ) {
            //add if string
            if( is_string( $attr ) ) {
                $this->validAttributes[] = $attr;
            }
        }
    }
protected function addValidAttributes( $attrs ) {
        foreach( $attrs as $attr ) {
            //add if string
            if( is_string( $attr ) ) {
                $this->validAttributes[] = $attr;
            }
        }
    }
protected function addValidAttributes ( $ attrs ) { foreach ( $ attrs as $ attr ) { //add if string
 if ( is_string ( $ attr ) ) { $ this -> validAttributes [ ] = $ attr ; } } }
Adds array of attributes to the valid attributes.

@param $attrs an array of attributes
Adds array of attributes to the valid attributes .