input: Write a python function to extract hashtags from a tweet object.
  assert getHashtags([{'text': 'Python'}, {'text': 'Coding'}]) == 'Python,Coding'
  assert getHashtags([{'text': 'AI'}, {'text': 'MachineLearning'}, {'text': 'DataScience'}]) == 'AI,MachineLearning,DataScience'
  assert getHashtags([{'text': 'OpenAI'}]) == 'OpenAI'
output: def getHashtags(hashtags):
      return ','.join([hashtag['text'] for hashtag in hashtags])