Given a list/tuple of zone, xllcorner and yllcorner of a geo-ref object,
    return a geo ref object.

    If the origin is None, return None, so calling this function doesn't
    effect code logic

def ensure_geo_reference(origin):
    """
    Given a list/tuple of zone, xllcorner and yllcorner of a geo-ref object,
    return a geo ref object.

    If the origin is None, return None, so calling this function doesn't
    effect code logic
    """

    if isinstance(origin, Geo_reference):
        geo_ref = origin
    elif origin is None:
        geo_ref = None
    else:
        geo_ref = apply(Geo_reference, origin)

    return geo_ref