from datetime import datetime


def cleanup_time(event_time):
    """
    Takes as input a datetime string as received from The AWS Health event_detail call.  It converts this string to a
    datetime object, changes the timezone to EST and then formats it into a readable string to display in Slack.

    :param event_time: datetime string
    :type event_time: str
    :return: A formatted string that includes the month, date, year and 12-hour time.
    :rtype: str
    """
    event_time = datetime.strptime(event_time[:16], '%Y-%m-%d %H:%M')
    return event_time.strftime("%Y-%m-%d %H:%M:%S")