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Solve the following problem using Python, implementing the functions described below, one line at a time
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<USER_TASK:>
Description:
 def onboarding_message(**payload):
 """Create and send an onboarding welcome message to new users. Save the time stamp of this message so we can update this message in the future. """

    # Get WebClient so you can communicate back to Slack.
    web_client = payload["web_client"]

    # Get the id of the Slack user associated with the incoming event
    user_id = payload["data"]["user"]["id"]

    # Open a DM with the new user.
    response = web_client.im_open(user_id)
    channel = response["channel"]["id"]

    # Post the onboarding message.
    start_onboarding(web_client, user_id, channel)