Convert a datetime object to a unix timestamp.

    Note that unlike a typical unix timestamp, this is seconds since 1970
    *local time*, not UTC.

    If the passed in object is already a timestamp, then that value is
    simply returned unmodified.

def to_timestamp(dt):
    """Convert a datetime object to a unix timestamp.

    Note that unlike a typical unix timestamp, this is seconds since 1970
    *local time*, not UTC.

    If the passed in object is already a timestamp, then that value is
    simply returned unmodified.
    """
    if isinstance(dt, int):
        return dt
    return int(total_seconds(dt.replace(tzinfo=None) -
               datetime.datetime(1970, 1, 1)))