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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_element_desc(element, ar_tree, ns):
 # type: (_Element, _DocRoot, str) -> str """Get element description from XML."""

    desc = get_child(element, "DESC", ar_tree, ns)
    txt = get_child(desc, 'L-2[@L="DE"]', ar_tree, ns)
    if txt is None:
        txt = get_child(desc, 'L-2[@L="EN"]', ar_tree, ns)
    if txt is None:
        txt = get_child(desc, 'L-2', ar_tree, ns)
    if txt is not None:
        return txt.text
    else:
        return ""