nl_tokens: https : // github . com / vuejs / vue / blob / dev / src / core / util / props . js#L177
pl_tokens: function getType ( fn ) { var type = fn !== null && fn !== undefined ? fn . type ? fn . <mask> : fn : null ; var match = type && type . toString ( ) . match ( FN_MATCH_REGEXP ) ; return match && match [ 1 ] ; }