code: def int3(params, ctxt, scope, stream, coord, interp):
      
      if interp._no_debug:
          return
  
      if interp._int3:
          interp.debugger = PfpDbg(interp)
          interp.debugger.cmdloop()
docs: Define the ``Int3()`` function in the interpreter. Calling
      ``Int3()`` will drop the user into an interactive debugger.