code: def set_ns_prefix(self, prefix, ns_uri):
          
          self._add_ns_prefix_attr(self.impl_node, prefix, ns_uri)
docs: 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.