Python:"make sure you entered a word containing only letters."

根据codecademy要求写的代码这样的：

pyg = 'ay'

original = raw_input('Enter a word:')

if len(original) > 0 and original.isalpha():
    word = original.lower()
    first = word[0]
    newword = word + first + pyg
    newword = word[1:len(newword)]+first+pyg
    print newword
else:
    print 'empty'

s="Charlie"
print s[0]
print s[1:4]
print s[1:len(s)]

然后一直提示：

Oops, try again. The value for the original variable looks off, make
sure that you entered a word containing only letters.

请求解惑啊，万分感谢！！！

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我想你输入的是不是纯字母字符，不是字母字符，转换大小写的时候会出问题的。

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make sure that you entered a word containing only letters.

有道翻译：确保你进入一个单词只包含字母。