def paginate_activity(visible_date=None):
    """
    Creates "get previous day" / "get next day" pagination for activities.

    Visible date is the date of the activities currently being shown,
    represented by a date object.

    If not provided, it will default to today.

    #Expects date as default "Aug. 25, 2014" format.
    """
    #if visible_date:
    #    visible_date = datetime.datetime.strptime(visible_date, "%b %d ")

    if not visible_date:
        visible_date = datetime.date.today()
    previous_day = visible_date - datetime.timedelta(days=1)
    if visible_date == datetime.date.today():
        next_day = None
    else:
        next_day = visible_date + datetime.timedelta(days=1)
    return {'previous_day': previous_day, 'next_day': next_day}