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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def load_keys():
 """Loads Twitter keys. Returns: tuple: consumer_key, consumer_secret, access_token, access_token_secret """

    consumer_key = os.environ.get('CONSUMER_KEY')
    consumer_secret = os.environ.get('CONSUMER_SECRET')
    access_token = os.environ.get('ACCESS_TOKEN')
    access_token_secret = os.environ.get('ACCESS_TOKEN_SECRET')

    return consumer_key, consumer_secret, access_token, access_token_secret