> For the complete documentation index, see [llms.txt](https://docs.zerve.ai/zerve-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zerve.ai/zerve-docs/data-and-assets/functions.md).

# Functions

Share reusable code across notebooks, with versions.

A **function** asset is reusable code, such as a function or class, that you write once and use across notebooks. Use functions for code your team shares, such as a standard way to load positions data or calculate risk metrics, so everyone uses the same version.

Find them under **Assets → Functions**.

## What a function contains

Each version of a function holds:

| Part             | Details                                                                  |
| ---------------- | ------------------------------------------------------------------------ |
| **Code**         | The function or class itself                                             |
| **Requirements** | The packages it needs, each with a version rule, such as `pandas >= 2.0` |
| **Imports**      | The imports the code needs                                               |
| **Language**     | The language and language version it's written in                        |

## Versions

Functions are **versioned**, like constants. Each change creates a new version, and a notebook uses the **specific version** attached to it. Updating a function doesn't change notebooks using an older version until you switch them.

This lets you improve shared code without breaking work that depends on the old behavior.

## Using a function in a notebook

Attach the function to a notebook, optionally with an **alias**. A notebook can't have the same function attached twice, or two functions with the same name.

## Functions, DAGs and skills

A function shares **code**. A [DAG](/zerve-docs/data-and-assets/dags.md) shares a whole pipeline of connected blocks. A [skill](/zerve-docs/agents-in-the-workspace/skills.md) shares **instructions** for the agent, such as how your team backtests a strategy. They work well together: a skill can tell the agent to use your team's functions.


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