Task 4: Send Slack notifications to team members.

airflow_usgs_task_four.py

# Task 4: Send Slack notifications to Slack Channel.
task_four = SlackWebhookOperator(
    task_id = 'send_slack_notification',
    http_conn_id = 'slack_conn',
    webhook_token = Variable.get("SLACK_API_TOKEN"),
    message = "New earthquake events was successfully harvested.",
    username = 'airflow'
)