$token
    ->delete_attr('foo')
    ->set_attr( bar => 'baz' ) if $token->is_start_tag;


##</code><code>##

while(my $token = $parser->get_token) {
    $token->del_attr('font');
    print $token->as_is;
}

##</code><code>##

while(my $token = $parser->get_token) {
    $token->del_attr('font') if $token->is_start_tag;
    print $token->as_is;
}