chore: import upstream snapshot with attribution

contributing/samples/workflows/parallel_worker/agent.py

@@ -0,0 +1,79 @@
+# Copyright 2026 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
+#
+#     http://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.
+
+from google.adk import Agent
+from google.adk import Event
+from google.adk import Workflow
+from google.adk.workflow import node
+from pydantic import BaseModel
+
+
+class TopicExplanation(BaseModel):
+  topic: str
+  explanation: str
+
+
+def process_input(node_input: str):
+  """Puts user input in the state."""
+  return Event(state={"topic": node_input})
+
+
+find_related_topics = Agent(
+    name="find_related_topics",
+    instruction=(
+        'Given the specific topic "{topic}", generate a list of 3 '
+        "related topics."
+    ),
+    output_schema=list[str],
+)
+
+
+@node(parallel_worker=True)
+def make_upper_case(node_input: str):
+  yield node_input.upper()
+
+
+explain_topic = Agent(
+    name="explain_topic",
+    instruction=(
+        "Explain how the following topic relates the the original topic: "
+        '"{topic}".'
+    ),
+    parallel_worker=True,
+    output_schema=TopicExplanation,
+)
+
+
+def aggregate(node_input: list[TopicExplanation]):
+  return Event(
+      message="\n\n---\n\n".join(
+          f"{explanation.topic}: {explanation.explanation}"
+          for explanation in node_input
+      ),
+  )
+
+
+root_agent = Workflow(
+    name="root_agent",
+    edges=[
+        (
+            "START",
+            process_input,
+            find_related_topics,
+            make_upper_case,
+            explain_topic,
+            aggregate,
+        ),
+    ],
+)