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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 importSafeElementTree(module_names=None):
 """Find a working ElementTree implementation that is not vulnerable to XXE, using `defusedxml`. @param module_names: The names of modules to try to use as a safe ElementTree. Defaults to C{L{xxe_safe_elementtree_modules}} @returns: An ElementTree module that is not vulnerable to XXE. """

    if module_names is None:
        module_names = xxe_safe_elementtree_modules
    try:
        return importElementTree(module_names)
    except ImportError:
        raise ImportError('Unable to find a ElementTree module '
                          'that is not vulnerable to XXE. '
                          'Tried importing %r' % (module_names, ))