chore: import upstream snapshot with attribution

doc/source/serve/doc_code/external_scaler_predictive.py

@@ -0,0 +1,35 @@
+# __serve_example_begin__
+import time
+from ray import serve
+from typing import Any
+
+@serve.deployment(num_replicas=3)
+class TextProcessor:
+    """A simple text processing deployment that can be scaled externally."""
+    def __init__(self):
+        self.request_count = 0
+
+    def __call__(self, text: Any) -> dict:
+        # Simulate text processing work
+        time.sleep(0.1)
+        self.request_count += 1
+        return {
+            "request_count": self.request_count,
+        }
+
+
+app = TextProcessor.bind()
+# __serve_example_end__
+
+def main():
+    import requests
+
+    serve.run(app)
+    
+    # Test the deployment
+    resp = requests.post(
+        "http://localhost:8000/",
+        json="hello world"
+    )
+    print(f"Response: {resp.json()}")
+