nl_tokens: Validates the regular expression type .
pl_tokens: function regexp ( rule , value , callback , source , options ) { const errors = [ ] ; const validate = rule . required || ( ! rule . required && source . hasOwnProperty ( rule . field ) ) ; if ( validate ) { if ( isEmptyValue ( value ) && ! <mask> . required ) { return callback ( ) ; } rules . required ( rule , value , source , errors , options ) ; if ( ! isEmptyValue ( value ) ) { rules . type ( rule , value , source , errors , options ) ; } } callback ( errors ) ; }