def METHOD_NAME(elem, loader=None, base_url=None,
            max_depth=DEFAULT_MAX_INCLUSION_DEPTH):
    if max_depth is None:
        max_depth = -1
    elif max_depth < 0:
        raise ValueError("expected non-negative depth or None for 'max_depth', got %r" % max_depth)
    if hasattr(elem, 'getroot'):
        elem = elem.getroot()
    if loader is None:
        loader = default_loader
    _include(elem, loader, base_url, max_depth, set())