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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 set_ns_prefix(self, prefix, ns_uri):
 """ Define a namespace prefix that will serve as shorthand for the given namespace URI in element names. :param string prefix: prefix that will serve as an alias for a the namespace URI. :param string ns_uri: namespace URI that will be denoted by the prefix. """

        self._add_ns_prefix_attr(self.impl_node, prefix, ns_uri)