add scorer example

examples/exp_pool/scorer.py

@@ -0,0 +1,25 @@
+import asyncio
+
+from metagpt.exp_pool.scorers import SimpleScorer
+from metagpt.logs import logger
+
+
+def echo(req: str):
+    """Echo from req."""
+
+    return req
+
+
+async def simple():
+    scorer = SimpleScorer()
+
+    score = await scorer.evaluate(echo, "data", ("data",))
+    logger.info(f"The score is: {score}")
+
+
+async def main():
+    await simple()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())