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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 add_parameter_dd(self, dag_tag, node_dict):
 """ helper function for adding parameters in condition Parameters dag_tag: etree SubElement the DAG tag is contained in this subelement node_dict: dictionary the decision diagram dictionary Return None """

        if isinstance(node_dict, defaultdict) or isinstance(node_dict, dict):
            node_tag = etree.SubElement(dag_tag, 'Node', attrib={'var': next(iter(node_dict.keys()))})
            edge_dict = next(iter(node_dict.values()))
            for edge in sorted(edge_dict.keys(), key=tuple):
                edge_tag = etree.SubElement(node_tag, 'Edge', attrib={'val': edge})
                value = edge_dict.get(edge)
                if isinstance(value, six.string_types):
                    terminal_tag = etree.SubElement(edge_tag, 'Terminal')
                    terminal_tag.text = value
                elif 'type' in value:
                    if 'val' in value:
                        etree.SubElement(edge_tag, 'SubDAG',
                                         attrib={'type': value['type'], 'var': value['var'], 'val': value['val']})
                    elif 'idref' in value:
                        etree.SubElement(edge_tag, 'SubDAG', attrib={'type': value['type'], 'idref': value['idref']})
                    else:
                        etree.SubElement(edge_tag, 'SubDAG', attrib={'type': value['type'], 'var': value['var']})
                else:
                    self.add_parameter_dd(edge_tag, value)