nl_tokens: ( arg → string ) return string - check and get argument
pl_tokens: function ( arg ) { var result switch ( arg ) { case 'on' : result = arg break case 'once' : result = arg break case 'class' : result = arg break case 'style' : result = arg break case 'enter' : result = arg break case 'leave' : result = arg break case 'animate' : result = arg break case 'parent' : result = arg break default : console . warn ( '[in-view] argument ${arg} undefined' ) } return <mask> }