docs: add cookbook for ab test

Author: joschkabraun

cookbook/ab_testing.py

@@ -0,0 +1,55 @@
+import os
+import random
+from typing import Tuple
+
+from openai import OpenAI
+
+from parea import trace, trace_insert, Parea, get_current_trace_id
+from parea.schemas import FeedbackRequest
+
+client = OpenAI()
+# instantiate Parea client
+p = Parea(api_key=os.getenv('PAREA_API_KEY'))
+# wrap OpenAI client to trace calls
+p.wrap_openai_client(client)
+
+
+@trace
+def generate_email(user: str) -> Tuple[str, str]:
+    """Randomly chooses a prompt to perform an A/B test for generating email. Returns the email and the trace ID.
+    The latter is used to tie-back the collected feedback from the user."""
+    if random.random() < 0.5:
+        trace_insert({'metadata': {'variant_name': 'variant_0'}})
+        prompt = f'Generate a long email for {user}'
+    else:
+        trace_insert({'metadata': {'variant_name': 'variant_1'}})
+        prompt = f'Generate a short email for {user}'
+
+    email = client.chat.completions.create(
+        model="gpt-4o",
+        messages=[
+            {
+                "role": "user",
+                "content": prompt,
+            }
+        ],
+    ).choices[0].message.content
+
+    return email, get_current_trace_id()
+
+
+def main():
+    # generate email and get trace ID
+    email, trace_id = generate_email('Max Mustermann')
+
+    # log user feedback on email using trace ID
+    p.record_feedback(
+        FeedbackRequest(
+            trace_id=trace_id,
+            score=1.0,
+        )
+    )
+
+
+if __name__ == '__main__':
+    main()