Add alternate source GO IDs.

def add_alt_goids(go2values, altgo2goobj):
    """Add alternate source GO IDs."""
    for goobj_key in altgo2goobj.values():
        values_curr = go2values[goobj_key.id]
        for goid_alt in goobj_key.alt_ids:
            go2values[goid_alt] = values_curr
    return go2values