code: def pause( msg = None ):
      
      f = sys._getframe(1)
      ff = f.f_code
      if (msg):
          print '%s, %d: %s(), %d: %s' % (ff.co_filename, ff.co_firstlineno,
                                          ff.co_name, f.f_lineno, msg)
      else:
          print '%s, %d: %s(), %d' % (ff.co_filename, ff.co_firstlineno,
                                      ff.co_name, f.f_lineno)
      spause()
docs: Prints the line number and waits for a keypress.
  
      If you press:
      "q" ............. it will call sys.exit()
      any other key ... it will continue execution of the program
  
      This is useful for debugging.