trace() - sets trace flags and returns the old ones.
int trace( int traceflags );
Sets the trace flags and returns the old trace flags. When tracing is on a lot of information is printed during execution. The trace bits are: 1 Trace all function calls to lfuns. 2 Trace all calls to "call_other". 4 Trace all function returns. 8 Print arguments at function calls and return values. 16 Print all executed stack machine instructions (produces a lot of output!). 32 Enable trace in heart beat functions. 64 Trace calls to apply. 128 Show object name in tracing.