refactor(streaming)!: remove old event_handler API (#532)

this wasn't actually seeing any usage and has been replaced by a more
ergonomic iterator API.

README.md

@@ -159,7 +159,7 @@ async def main() -> None:
 asyncio.run(main())
 ```
 
-Streaming with `client.messages.stream(...)` exposes [various helpers for your convenience](helpers.md) including event handlers and accumulation.
+Streaming with `client.messages.stream(...)` exposes [various helpers for your convenience](helpers.md) including accumulation & SDK-specific events.
 
 Alternatively, you can use `client.messages.create(..., stream=True)` which only returns an async iterable of the events in the stream and thus uses less memory (it does not build up a final message object for you).
 

src/anthropic/lib/streaming/__init__.py

@@ -7,9 +7,7 @@
 )
 from ._messages import (
     MessageStream as MessageStream,
-    MessageStreamT as MessageStreamT,
     AsyncMessageStream as AsyncMessageStream,
-    AsyncMessageStreamT as AsyncMessageStreamT,
     MessageStreamManager as MessageStreamManager,
     AsyncMessageStreamManager as AsyncMessageStreamManager,
 )