import pytz


def add_timezone(time_record):
    """ Add a default America/New_York timezone info to a datetime object.

        Args:
            time_record: Datetime object.

        Returns:
            Datetime object with a timezone if time_record did not have tzinfo,
            otherwise return time_record itself.
    """
    if time_record.tzname() is None:
        return time_record.replace(tzinfo=pytz.timezone('America/New_York'))

    return time_record