对于我的编程类，我必须根据以下描述创建一个函数：The parameter is a tweet. This function should return a list containing all of the hashtags in the tweet, in the order they appear in the tweet. Each hashtag in the returned list should have the initial hash symbol removed, and hashtags should be unique. (If a tweet uses the same hashtag twice, it is included in the list only once. The order of the hashtags should match the order of the first occurrence of each tag in the tweet.)

我不确定如何使它在遇到标点时结束标签(参见第二个doctest示例)。我当前的代码没有输出任何内容：def extract(start, tweet):

""" (str, str) -> list of str

Return a list of strings containing all words that start with a specified character.

>>> extract('@', "Make America Great Again, vote @RealDonaldTrump")

['RealDonaldTrump']

>>> extract('#', "Vote Hillary! #ImWithHer #TrumpsNotMyPresident")

['ImWithHer', 'TrumpsNotMyPresident']

"""

words = tweet.split()

return [word[1:] for word in words if word[0] == start]

def strip_punctuation(s):

""" (str) -> str

Return a string, stripped of its punctuation.

>>> strip_punctuation("Trump's in the lead... damn!")

'Trumps in the lead damn'

"""

return ''.join(c for c in s if c not in '!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~')

def extract_hashtags(tweet):

""" (str) -> list of str

Return a list of strings containing all unique hashtags in a tweet.

Outputted in order of appearance.

>>> extract_hashtags("I stand with Trump! #MakeAmericaGreatAgain #MAGA #TrumpTrain")

['MakeAmericaGreatAgain', 'MAGA', 'TrumpTrain']

>>> extract_hashtags('NEVER TRUMP. I'm with HER. Does #this! work?')

['this']

"""

hashtags = extract('#', tweet)

no_duplicates = []

for item in hashtags:

if item not in no_duplicates and item.isalnum():

no_duplicates.append(item)

result = []

for hash in no_duplicates:

for char in hash:

if char.isalnum() == False and char != '#':

hash == hash[:char.index()]

result.append()

return result

在这一点上我很迷茫，任何帮助都将不胜感激。提前谢谢你。在

注意：我们不允许使用正则表达式或导入任何模块。在