clear_trace() { # reset trace output
      echo > trace
  }
  
  disable_tracing() { # stop trace recording
      echo 0 > tracing_on
  }
  
  enable_tracing() { # start trace recording
      echo 1 > tracing_on
  }
  
  reset_tracer() { # reset the current tracer
      echo nop > current_tracer
  }