docs: add cancel operation sample

samples/beta/cancel_operation.py

@@ -0,0 +1,63 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2019 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import sys
+
+# [START automl_cancel_operation]
+
+from google.cloud import automl_v1beta1
+
+
+def sample_cancel_operation(project, operation_id):
+    """
+    Cancel Long-Running Operation
+
+    Args:
+      project Required. Your Google Cloud Project ID.
+      operation_id Required. The ID of the Operation.
+    """
+
+    client = automl_v1beta1.AutoMlClient()
+
+    operations_client = client.transport._operations_client
+
+    # project = '[Google Cloud Project ID]'
+    # operation_id = '[Operation ID]'
+    name = "projects/{}/locations/us-central1/operations/{}".format(
+        project, operation_id
+    )
+
+    operations_client.cancel_operation(name)
+
+    print(u"Cancelled operation: {}".format(name))
+
+
+# [END automl_cancel_operation]
+
+
+def main():
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--project", type=str, default="[Google Cloud Project ID]")
+    parser.add_argument("--operation_id", type=str, default="[Operation ID]")
+    args = parser.parse_args()
+
+    sample_cancel_operation(args.project, args.operation_id)
+
+
+if __name__ == "__main__":
+    main()