text: #!/usr/bin/env python
  
  """ID checker."""
  
  import string
  from keyword import kwlist
  
  alphas = string.letters + '_'
  nums = string.digits
  alphaNums = alphas + nums
  
  while True:
      print 'Welcome to the Identifier Checker v1.1'
      print 'Testees must be at least 1 char long.'
      myInput = raw_input('Identifier to test("quit" to quit)?\n')
  
      if len(myInput) > 0:
          if myInput == 'quit':
              break
  
          if myInput in kwlist:
              print """Invalid: you should not use keyword
  '%s' as identifier""" % myInput
              continue
  
          if myInput[0] not in alphas:
              print "Invalid: first symbol must be alphabetic"
          else:
              ret = True
              for otherChar in myInput[1:]:
                  if otherChar not in alphaNums:
                      ret = False
                      print "Invalid: remaining symbols must be alphanumeric"
                      break
              if ret:
                  print "%s is a valid identifier." % myInput
      else:
          print 'You should input at least 1 char, please.\n'
  