chore: import upstream snapshot with attribution

doc/source/serve/doc_code/model_composition/chaining_example.py

@@ -0,0 +1,50 @@
+# flake8: noqa
+# __chaining_example_start__
+# File name: chain.py
+from ray import serve
+from ray.serve.handle import DeploymentHandle, DeploymentResponse
+
+
+@serve.deployment
+class Adder:
+    def __init__(self, increment: int):
+        self._increment = increment
+
+    def __call__(self, val: int) -> int:
+        return val + self._increment
+
+
+@serve.deployment
+class Multiplier:
+    def __init__(self, multiple: int):
+        self._multiple = multiple
+
+    def __call__(self, val: int) -> int:
+        return val * self._multiple
+
+
+@serve.deployment
+class Ingress:
+    def __init__(self, adder: DeploymentHandle, multiplier: DeploymentHandle):
+        self._adder = adder
+        self._multiplier = multiplier
+
+    async def __call__(self, input: int) -> int:
+        adder_response: DeploymentResponse = self._adder.remote(input)
+        # Pass the adder response directly into the multiplier (no `await` needed).
+        multiplier_response: DeploymentResponse = self._multiplier.remote(
+            adder_response
+        )
+        # `await` the final chained response.
+        return await multiplier_response
+
+
+app = Ingress.bind(
+    Adder.bind(increment=1),
+    Multiplier.bind(multiple=2),
+)
+
+handle: DeploymentHandle = serve.run(app)
+response = handle.remote(5)
+assert response.result() == 12, "(5 + 1) * 2 = 12"
+# __chaining_example_end__