How to use the pydot.frozendict function in pydot

def push_edge_stmt(str, loc, toks):
    
    tok_attrs = [a for a in toks if isinstance(a, P_AttrList)]
    attrs = {}
    for a in tok_attrs:
        attrs.update(a.attrs)

    e = []

    if isinstance(toks[0][0], pydot.Graph):
    
        n_prev = pydot.frozendict(toks[0][0].obj_dict)
    else:        
        n_prev = toks[0][0] + do_node_ports( toks[0] )

    if isinstance(toks[2][0], ParseResults):
    
        n_next_list = [[n.get_name(),] for n in toks[2][0] ]
        for n_next in [n for n in n_next_list]:
            n_next_port = do_node_ports(n_next)
            e.append(pydot.Edge(n_prev, n_next[0]+n_next_port, **attrs))

    elif isinstance(toks[2][0], pydot.Graph):
    
        e.append(pydot.Edge(n_prev, pydot.frozendict(toks[2][0].obj_dict), **attrs))

    elif isinstance(toks[2][0], pydot.Node):

if not item_dict.has_key( key_name ):
            continue

        for key, objs in item_dict[key_name].items():
            for obj in objs:
                if 'parent_graph' in obj and obj['parent_graph'].get_parent_graph()==g:
                    if obj['parent_graph'] is g:
                        pass
                    else:
                        obj['parent_graph'].set_parent_graph(parent_graph)

                if key_name == 'edges' and len(key) == 2:
                    for idx, vertex in enumerate( obj['points'] ):
                        if isinstance( vertex, (pydot.Graph, pydot.Subgraph, pydot.Cluster)):
                            vertex.set_parent_graph(parent_graph)
                        if isinstance( vertex, pydot.frozendict):
                            if vertex['parent_graph'] is g:
                                pass
                            else:
                                vertex['parent_graph'].set_parent_graph(parent_graph)

def __new__(cls, *args, **kw):
        new = dict.__new__(cls)

        args_ = []
        for arg in args:
            if isinstance(arg, dict):
                arg = copy.copy(arg)
                for k, v in arg.iteritems():
                    if isinstance(v, frozendict):
                        arg[k] = v
                    elif isinstance(v, dict):
                        arg[k] = frozendict(v)
                    elif isinstance(v, list):
                        v_ = list()
                        for elm in v:
                            if isinstance(elm, dict):
                                v_.append( frozendict(elm) )
                            else:
                                v_.append( elm )
                        arg[k] = tuple(v_)
                args_.append( arg )
            else:
                args_.append( arg )

        dict.__init__(new, *args_, **kw)
        return new

new = dict.__new__(cls)

        args_ = []
        for arg in args:
            if isinstance(arg, dict):
                arg = copy.copy(arg)
                for k, v in arg.iteritems():
                    if isinstance(v, frozendict):
                        arg[k] = v
                    elif isinstance(v, dict):
                        arg[k] = frozendict(v)
                    elif isinstance(v, list):
                        v_ = list()
                        for elm in v:
                            if isinstance(elm, dict):
                                v_.append( frozendict(elm) )
                            else:
                                v_.append( elm )
                        arg[k] = tuple(v_)
                args_.append( arg )
            else:
                args_.append( arg )

        dict.__init__(new, *args_, **kw)
        return new

args_ = []
        for arg in args:
            if isinstance(arg, dict):
                arg = copy.copy(arg)
                for k in arg:
                    v = arg[k]
                    if isinstance(v, frozendict):
                        arg[k] = v
                    elif isinstance(v, dict):
                        arg[k] = frozendict(v)
                    elif isinstance(v, list):
                        v_ = list()
                        for elm in v:
                            if isinstance(elm, dict):
                                v_.append( frozendict(elm) )
                            else:
                                v_.append( elm )
                        arg[k] = tuple(v_)
                args_.append( arg )
            else:
                args_.append( arg )

        dict.__init__(new, *args_, **kw)
        return new

def __new__(cls, *args, **kw):
        new = dict.__new__(cls)

        args_ = []
        for arg in args:
            if isinstance(arg, dict):
                arg = copy.copy(arg)
                for k in arg:
                    v = arg[k]
                    if isinstance(v, frozendict):
                        arg[k] = v
                    elif isinstance(v, dict):
                        arg[k] = frozendict(v)
                    elif isinstance(v, list):
                        v_ = list()
                        for elm in v:
                            if isinstance(elm, dict):
                                v_.append( frozendict(elm) )
                            else:
                                v_.append( elm )
                        arg[k] = tuple(v_)
                args_.append( arg )
            else:
                args_.append( arg )

        dict.__init__(new, *args_, **kw)
        return new

n_prev = pydot.frozendict(toks[0][0].obj_dict)
    else:
        n_prev = toks[0][0] + do_node_ports( toks[0] )

    if isinstance(toks[2][0], ParseResults):

        n_next_list = [[n.get_name(),] for n in toks[2][0] ]
        for n_next in [n for n in n_next_list]:
            n_next_port = do_node_ports(n_next)
            e.append(pydot.Edge(n_prev, n_next[0]+n_next_port, **attrs))

    elif isinstance(toks[2][0], pydot.Graph):

        e.append(pydot.Edge(n_prev,
                            pydot.frozendict(toks[2][0].obj_dict),
                            **attrs))

    elif isinstance(toks[2][0], pydot.Node):

        node = toks[2][0]

        if node.get_port() is not None:
            name_port = node.get_name() + ":" + node.get_port()
        else:
            name_port = node.get_name()

        e.append(pydot.Edge(n_prev, name_port, **attrs))

    # if the target of this edge is the name of a node
    elif isinstance(toks[2][0], str_type):

for key, objs in item_dict[key_name].items():
            for obj in objs:
                if ('parent_graph' in obj and
                        obj['parent_graph'].get_parent_graph()==g):
                    if obj['parent_graph'] is g:
                        pass
                    else:
                        obj['parent_graph'].set_parent_graph(parent_graph)

                if key_name == 'edges' and len(key) == 2:
                    for idx, vertex in enumerate( obj['points'] ):
                        if isinstance( vertex,
                                      (pydot.Graph,
                                       pydot.Subgraph, pydot.Cluster)):
                            vertex.set_parent_graph(parent_graph)
                        if isinstance( vertex, pydot.frozendict):
                            if vertex['parent_graph'] is g:
                                pass
                            else:
                                vertex['parent_graph'].set_parent_graph(
                                    parent_graph)

new = dict.__new__(cls)

        args_ = []
        for arg in args:
            if isinstance(arg, dict):
                arg = copy.copy(arg)
                for k, v in arg.iteritems():
                    if isinstance(v, frozendict):
                        arg[k] = v
                    elif isinstance(v, dict):
                        arg[k] = frozendict(v)
                    elif isinstance(v, list):
                        v_ = list()
                        for elm in v:
                            if isinstance(elm, dict):
                                v_.append( frozendict(elm) )
                            else:
                                v_.append( elm )
                        arg[k] = tuple(v_)
                args_.append( arg )
            else:
                args_.append( arg )

        dict.__init__(new, *args_, **kw)
        return new