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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_message(message=None, channel=None, username=None, icon_emoji=None):
 """Format the message and post to the appropriate slack channel. Args: message (str):
 Message to post to slack channel (str):
 Desired channel. Must start with # """

    LOG.debug('Slack Channel: %s\nSlack Message: %s', channel, message)
    slack = slacker.Slacker(SLACK_TOKEN)
    try:
        slack.chat.post_message(channel=channel, text=message, username=username, icon_emoji=icon_emoji)
        LOG.info('Message posted to %s', channel)
    except slacker.Error:
        LOG.info("error posted message to %s", channel)