---
title: thunder.last_backward_traces
description: >-
  Obtains the list of backward traces that have been produced for the last run
  of the function and the selected prologue.
canonical: >-
  https://lightning.ai/docs/thunder/stable/api-reference/generated/thunder.last_backward_traces
---
# thunder.last_backward_traces {#thunder-last-backward-traces}

### `thunder.last_backward_traces(fn)` {#thunder.last_backward_traces}

[\[source\]](https://github.com/Lightning-AI/lightning-thunder/blob/0.2.6/thunder/__init__.py#L955-L962)

Obtains the list of backward traces that have been produced for the last run of the function and the selected prologue.

Return type:

[`list`](https://docs.python.org/3/builtins/stdtypes.html#list "(in Python v3.15)")\[[`TraceCtx`](/docs/thunder/0.2.6/core/generated/thunder.core.trace.TraceCtx.md#thunder.core.trace.TraceCtx "thunder.core.trace.TraceCtx")\]

---

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