implementor      2010 ext/date/php_date.c static int implement_date_interface_handler(zend_class_entry *interface, zend_class_entry *implementor TSRMLS_DC)
implementor      2012 ext/date/php_date.c 	if (implementor->type == ZEND_USER_CLASS &&
implementor      2013 ext/date/php_date.c 		!instanceof_function(implementor, date_ce_date TSRMLS_CC) &&
implementor      2014 ext/date/php_date.c 		!instanceof_function(implementor, date_ce_immutable TSRMLS_CC)