async def on_run_step_delta(self, delta: RunStepDelta, snapshot: RunStep) -> None:
        """Callback that is fired whenever a run step delta is returned from the API

        The first argument is just the delta as sent by the API and the second argument
        is the accumulated snapshot of the run step. For example, a tool calls event may
        look like this:

        # delta
        tool_calls=[
            RunStepDeltaToolCallsCodeInterpreter(
                index=0,
                type='code_interpreter',
                id=None,
                code_interpreter=CodeInterpreter(input=' sympy', outputs=None)
            )
        ]
        # snapshot
        tool_calls=[
            CodeToolCall(
                id='call_wKayJlcYV12NiadiZuJXxcfx',
                code_interpreter=CodeInterpreter(input='from sympy', outputs=[]),
                type='code_interpreter',
                index=0
            )
        ],
        """
Callback that is fired whenever a run step delta is returned from the API

        The first argument is just the delta as sent by the API and the second argument
        is the accumulated snapshot of the run step. For example, a tool calls event may
        look like this:

        # delta
        tool_calls=[
            RunStepDeltaToolCallsCodeInterpreter(
                index=0,
                type='code_interpreter',
                id=None,
                code_interpreter=CodeInterpreter(input=' sympy', outputs=None)
            )
        ]
        # snapshot
        tool_calls=[
            CodeToolCall(
                id='call_wKayJlcYV12NiadiZuJXxcfx',
                code_interpreter=CodeInterpreter(input='from sympy', outputs=[]),
                type='code_interpreter',
                index=0
            )
        ],
        
src/openai/lib/streaming/_assistants.py