def lookup_global(name):
    """
    Used in unpickling the factory itself.

    EXAMPLES::

        sage: from sage.structure.factory import lookup_global
        sage: lookup_global('ZZ')
        Integer Ring
        sage: lookup_global('sage.rings.all.ZZ')
        Integer Ring
    """
    name = bytes_to_str(name, encoding='ASCII')
    try:
        return factory_unpickles[name]
    except KeyError:
        pass

    if '.' in name:
        module, name = name.rsplit('.', 1)
        all = __import__(module, fromlist=[name])
    else:
        import sage.all as all
    return getattr(all, name)