nl_tokens: Watch the given expression or function
pl_tokens: function watchDataChange ( expressOrFunc , callback , options ) { if ( typeof expressOrFunc === 'function' ) { expressOrFunc = this . __addComputedProp ( expressOrFunc ) ; } if ( typeof <mask> === 'function' ) { let handlerName = getAnonymousWatcherName ( this ) ; this [ handlerName ] = callback ; callback = handlerName ; } return this . __watchDataChange ( expressOrFunc , callback , options ) ; }