python -- for...else

#!/usr/bin/env pythonimport stringimport keywordalphas = string.letters + '_'nums = string.digitsprint 'Welcome to the Identifier Checker v1.0'print 'Testees must be at least 2 chars long.'myInput = raw_input('Identifier to test ? ')        if len(myInput) > 1:    if myInput[0] not in alphas:        print 'invalid: first symbol must be alphabetic'    else:        if keyword.iskeyword(myInput):            print 'invalid: builtin keyword'        else:                       for otherChar in myInput[1:]:                if otherChar not in alphas + nums:                        print 'invalid: remaining symbols must be alphanumeric'                        break            else:                print 'Okay as an identifier'

for 循环的else语句是一个可选项，它只在for循环完整的结束，没有遇到break时执行。