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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 _create_xml_node(tag, prefix=None, ns=None):
 """Create a XML node."""

    if prefix and ns:
        ET.register_namespace(prefix, ns)
    if ns:
        return ET.Element("{"+ns+"}"+tag)
    else:
        return ET.Element(tag)