Custom Conditional Placeholder for Event Attribute

<?php

/*
 {is_true} show this message {/is_true}
*/

function my_em_has_attribute_event_output_condition($replacement, $condition, $match, $EM_Event){
    if( is_object($EM_Event) && preg_match('/^is_true/',$condition, $matches) ){
    	if( !in_array($args['attribute_name'],$EM_Event->event_attributes) && !empty($EM_Event->event_attributes['attribute_name']) ){
            $replacement = preg_replace("/\{\/?$condition\}/", '', $match);
        }else{
            $replacement = '';
        }
    }
    return $replacement;
}
add_action('em_event_output_condition', 'my_em_has_attribute_event_output_condition', 1, 4);

?>