nl_tokens: Format the stack trace if not yet done and return it . Cache the formatted stack trace on the holder .
pl_tokens: function ( ) { var formatted_stack_trace = UNDEFINED ; var holder = this ; while ( holder ) { var formatted_stack_trace = GET_PRIVATE ( holder , formattedStackTraceSymbol ) ; if ( IS_UNDEFINED ( formatted_stack_trace ) ) { // No formatted stack trace available. var stack_trace = GET_PRIVATE ( holder , stackTraceSymbol ) ; if ( IS_UNDEFINED ( stack_trace ) ) { // Neither formatted nor structured stack trace available. // Look further up the prototype chain. holder = % object_get_prototype_of ( holder ) ; <mask> ; } formatted_stack_trace = FormatStackTrace ( holder , stack_trace ) ; SET_PRIVATE ( holder , stackTraceSymbol , UNDEFINED ) ; SET_PRIVATE ( holder , formattedStackTraceSymbol , formatted_stack_trace ) ; } return formatted_stack_trace ; } return UNDEFINED ; }