docs: def enable_tracing(self):
          """ Enable tracing if it is disabled and debugged program is running, 
          else do nothing.
          Do this on all threads but the debugger thread.
          :return: True if tracing has been enabled, False else.
          """
          _logger.x_debug("entering enable_tracing()")
          # uncomment next line to get debugger tracing info
          #self.dump_tracing_state("before enable_tracing()")
          
          if not self.tracing_enabled and self.execution_started:
              # Restore or set trace function on all existing frames appart from 
              # debugger
              threading.settrace(self._tracer)  # then enable on all threads to come
              for thr in threading.enumerate():
                  if thr.ident != self.debugger_thread_ident:  # skip debugger thread
                      a_frame = sys._current_frames()[thr.ident]
                      while a_frame:
                          a_frame.f_trace = self._tracer
                          a_frame = a_frame.f_back
              iksettrace3._set_trace_on(self._tracer, self.debugger_thread_ident)
              self.tracing_enabled = True
          
          #self.dump_tracing_state("after enable_tracing()")
          return self.tracing_enabled