GCP google visionについて

GCP google visionについて
以下のリンクに記載の通り、コードを実行したところ、下記のエラーが発生しました。
どのように対処すれば良いのかわからず、困っております。
お手数ですが、対処方法についてご教示お願いいたします。

https://cloud.google.com/vision/docs/pdf#vision_text_detection_pdf_gcs-python

python
1def async_detect_document(gcs_source_uri, gcs_destination_uri):
2    """OCR with PDF/TIFF as source files on GCS"""
3    import json
4    import re
5    from google.cloud import vision
6    from google.cloud import storage
7
8    # Supported mime_types are: 'application/pdf' and 'image/tiff'
9    mime_type = 'application/pdf'
10
11    # How many pages should be grouped into each json output file.
12    batch_size = 2
13
14    client = vision.ImageAnnotatorClient()
15
16    feature = vision.Feature(
17        type_=vision.Feature.Type.DOCUMENT_TEXT_DETECTION)
18
19    gcs_source = vision.GcsSource(uri=gcs_source_uri)
20    input_config = vision.InputConfig(
21        gcs_source=gcs_source, mime_type=mime_type)
22
23    gcs_destination = vision.GcsDestination(uri=gcs_destination_uri)
24    output_config = vision.OutputConfig(
25        gcs_destination=gcs_destination, batch_size=batch_size)
26
27    async_request = vision.AsyncAnnotateFileRequest(
28        features=[feature], input_config=input_config,
29        output_config=output_config)
30
31    operation = client.async_batch_annotate_files(
32        requests=[async_request])
33
34    print('Waiting for the operation to finish.')
35    operation.result(timeout=420)
36
37    # Once the request has completed and the output has been
38    # written to GCS, we can list all the output files.
39    storage_client = storage.Client()
40
41    match = re.match(r'gs://([^/]+)/(.+)', gcs_destination_uri)
42    bucket_name = match.group(1)←ここでエラーになります。
43    prefix = match.group(2)
44
45    bucket = storage_client.get_bucket(bucket_name)
46
47    # List objects with the given prefix.
48    blob_list = list(bucket.list_blobs(prefix=prefix))
49    print('Output files:')
50    for blob in blob_list:
51        print(blob.name)
52
53    # Process the first output file from GCS.
54    # Since we specified batch_size=2, the first response contains
55    # the first two pages of the input file.
56    output = blob_list[0]
57
58    json_string = output.download_as_string()
59    response = json.loads(json_string)
60
61    # The actual response for the first page of the input file.
62    first_page_response = response['responses'][0]
63    annotation = first_page_response['fullTextAnnotation']
64
65    # Here we print the full text from the first page.
66    # The response contains more information:
67    # annotation/pages/blocks/paragraphs/words/symbols
68    # including confidence scores and bounding boxes
69    print('Full text:\n')
70    print(annotation['text'])

（エラー画面）

AttributeError
1<ipython-input-144-ed7251c56f06> in <module>
2     40 
3     41 match = re.match(r'gs://([^/]+)/(.+)', gcs_destination_uri)
4---> 42 bucket_name = match.group(1)
5     43 prefix = match.group(2)
6     44 
7
8AttributeError: 'NoneType' object has no attribute 'group'
9
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