Parse elastic datetime string.

def parse_date(date_str):
    """Parse elastic datetime string."""
    if not date_str:
        return None

    try:
        date = ciso8601.parse_datetime(date_str)
        if not date:
            date = arrow.get(date_str).datetime
    except TypeError:
        date = arrow.get(date_str[0]).datetime
    return date