python caller error

Hello , 

I got error from Python caller .

i would like to get all paths from start node to end node then I have written this script but I got Ann error .

could you please help me to fix this problem ?

import fme

import fmeobjects

import networkx as nx


class FeatureProcessor(object):

    def __init__(self):

        self.graph = nx.DiGraph()

        self.start_end_pairs = []


    def input(self, feature):

        start_node = feature.getAttribute('start_node')

        end_node = feature.getAttribute('end_node')

        arc_id = feature.getAttribute('arc_id')



        self.graph.add_edge(start_node, end_node, arc_id=arc_id)

        self.start_end_pairs.append((start_node, end_node))


    def find_all_paths(self, start, end):

        return list(nx.all_simple_paths(self.graph, source=start, target=end))


    def close(self):

        for start, end in self.start_end_pairs:

            all_paths = self.find_all_paths(start, end)

            for path in all_paths:

                feature = fmeobjects.FMEFeature()

                feature.setAttribute('path', ' -> '.join(path))

                self.pyoutput(feature)

Python Exception <AttributeError>: module 'importlib.resources' has no attribute 'files'

Error executing string `import fme

Error :

Factory proxy not initialized

PythonCaller_3 (PythonFactory): PythonFactory failed to process feature

PythonCaller_3 (PythonFactory): A fatal error has occurred. Check the logfile above for details

AttributeCreator_164_OUTPUT_-1_6456_Player (RecorderFactory): A fatal error has occurred. Check the logfile above for details

Thanks in advance 

FME 2021