Add new function for xlang in snippet(apache#26693)

sdks/python/apache_beam/examples/snippets/snippets.py

@@ -1245,6 +1245,46 @@ def table_fn(element, fictional_characters):
       }})
   # [END model_bigqueryio_time_partitioning]
 
+def model_bigqueryio_xlang(
+    pipeline, write_project='', write_dataset='', write_table=''):
+  """Examples for cross-language BigQuery sources and sinks."""
+
+  table_spec = 'clouddataflow-readonly:samples.weather_stations'
+  if write_project and write_dataset and write_table:
+    table_spec = '{}:{}.{}'.format(write_project, write_dataset, write_table)
+
+  table_schema = {
+      'fields': [{
+          'name': 'source', 'type': 'STRING', 'mode': 'NULLABLE'
+      }, {
+          'name': 'quote', 'type': 'STRING', 'mode': 'REQUIRED'
+      }]
+  }
+
+  quotes = pipeline | beam.Create([
+      {
+          'source': 'Mahatma Gandhi', 'quote': 'My life is my message.'
+      },
+      {
+          'source': 'Yoda', 'quote': "Do, or do not. There is no 'try'."
+      },
+  ])
+
+  # [START model_bigqueryio_storage_write_api_with_frequency]
+  # The SDK for Python does not support `withNumStorageWriteApiStreams`
+  quotes | "StorageWriteAPIWithFrequency" >> beam.io.WriteToBigQuery(
+      table_spec,
+      schema=table_schema,
+      method=beam.io.WriteToBigQuery.Method.STORAGE_WRITE_API,
+      triggering_frequency=5)
+  # [END model_bigqueryio_storage_write_api_with_frequency]
+
+  # [START model_bigqueryio_write_with_storage_write_api]
+  quotes | "WriteTableWithStorageAPI" >> beam.io.WriteToBigQuery(
+      table_spec,
+      schema=table_schema,
+      method=beam.io.WriteToBigQuery.Method.STORAGE_WRITE_API)
+  # [END model_bigqueryio_write_with_storage_write_api]
 
 def model_composite_transform_example(contents, output_path):
   """Example of a composite transform.

sdks/python/apache_beam/examples/snippets/snippets_test.py

@@ -33,6 +33,7 @@
 
 import mock
 import parameterized
+import pytest
 
 import apache_beam as beam
 from apache_beam import WindowInto
@@ -754,6 +755,13 @@ def test_model_bigqueryio(self):
       p.options.view_as(GoogleCloudOptions).temp_location = 'gs://mylocation'
       snippets.model_bigqueryio(p)
 
+  @pytest.mark.uses_gcp_java_expansion_service
+  @unittest.skipUnless(
+      os.environ.get('EXPANSION_PORT'),
+      "EXPANSION_PORT environment var is not provided.")
+  def test_model_bigqueryio_xlang(self):
+    pass
+
   def _run_test_pipeline_for_options(self, fn):
     temp_path = self.create_temp_file('aa\nbb\ncc')
     result_path = temp_path + '.result'