Python 正在获取Word 2 Num的输入

我试着把代码写在需要用户输入的地方，而不是把它放在打印行中。有人能帮我吗

def toNum(words, num={}):
    if not num:
        teens = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen","sixteen", "seventeen", "eighteen", "nineteen",]
        tens = ["", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"]
        hund = ["hundred", "thousand"]


        num["and"] = (1, 0)
        for idx, word in enumerate(teens): num[word] = (1, idx)
        for idx, word in enumerate(tens): num[word] = (1, idx * 10)
        for idx, word in enumerate(hund): num[word] = (10 ** (idx * 3 or 2), 0)

        input = result = 0
        for word in words.split():
                if word not in num:
                        raise Exception(word)

                hund, increment = num[word]
                input = input * hund + increment
                if hund > 100:
                        result += input
                        input = 0

        return result + input

print toNum("seventy three hundred")
#here I want it to ask for user input instead of my having to write it in the code. Not sure how to apply it to the rest of the code. 

print toNum(raw_input("Enter a number: "))