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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 post_slack():
 """Post slack message."""

    try:
        token = os.environ['SLACK_TOKEN']
        slack = Slacker(token)

        obj = slack.chat.post_message('#general', 'Hello fellow slackers!')
        print(obj.successful, obj.__dict__['body']['channel'], obj.__dict__[
            'body']['ts'])
    except KeyError as ex:
        print('Environment variable %s not set.' % str(ex))