# merge_lists

> **Function** in `langchain_core`

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

Add many lists, handling `None`.

## Signature

```python
merge_lists(
    left: list | None,
    *others: list | None = (),
) -> list | None
```

## Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `left` | `list \| None` | Yes | The first list to merge. |
| `others` | `list \| None` | No | The other lists to merge. (default: `()`) |

## Returns

`list | None`

The merged list.

---

[View source on GitHub](https://github.com/langchain-ai/langchain/blob/6fb37dba71da807af60aa7b909f71f0625a666bf/libs/core/langchain_core/utils/_merge.py#L89)