ZEND_SEND_BY_REF  675 Zend/zend_compile.h 	(ARG_SEND_TYPE(zf, arg_num) == ZEND_SEND_BY_REF)
ZEND_SEND_BY_REF  678 Zend/zend_compile.h 	(ARG_SEND_TYPE(zf, arg_num) & (ZEND_SEND_BY_REF|ZEND_SEND_PREFER_REF))