LMPs return a 3-tuple when exempt_from_tracking=True

[jwang-paradise]

LMPs registered with @ell.simple/complex/tool return different shapes with different exempt_from_tracking settings.

For example, when exempt_from_tracking=False, LMP returns a message as expected:

@ell.complex(...)
def complex_lmp(message_history: list[Message]) -> list[Message]: ...

resp_message = complex_lmp(message_history)

But when exempt_from_tracking=True, LMP returns a 3 tuple:

@ell.complex(..., exempt_from_tracking=True)
def complex_lmp_EXEMPTED(message_history: list[Message]) -> list[Message]: ...

resp_message, final_call_params, api_metadata = complex_lmp_EXEMPTED(message_history)
# unexpectedly got a 3 tuple

The docs should really mention this weird side effect. Took me quite a while to figure it out.

[jwang-paradise]

An LMP tool @ell.tool(exempt_from_tracking=True) will also return a 3-tuple, causing ValidationError in ToolCall.call_and_collect_as_content_block method: message.py

ValidationError: 1 validation error for ContentBlock tool_result