# callbacks

> **Module** in `langchain_core`

📖 [View in docs](https://reference.langchain.com/python/langchain-core/callbacks)

Callback handlers allow listening to events in LangChain.

## Methods

- [`import_attr()`](https://reference.langchain.com/python/langchain-core/callbacks/import_attr)
- [`adispatch_custom_event()`](https://reference.langchain.com/python/langchain-core/callbacks/adispatch_custom_event)
- [`dispatch_custom_event()`](https://reference.langchain.com/python/langchain-core/callbacks/dispatch_custom_event)
- [`get_usage_metadata_callback()`](https://reference.langchain.com/python/langchain-core/callbacks/get_usage_metadata_callback)

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[View source on GitHub](https://github.com/langchain-ai/langchain/blob/02991cb4cf2063d51a07268edafb05fe53de1826/libs/core/langchain_core/callbacks/__init__.py)