## Adding Python packages/libraries with UV The UV tool helps us manage Python packages and dependencies across different projects and versions. We'll use the **Titanoboa** package in this lesson to showcase how UV can be used to manage dependencies. **Titano Boa** is a package that allows us to evaluate code written in Python. First, let's create a simple Python script that will utilize **Titanoboa**. ```python import boa import sys print(boa.eval('"empty(uint256())"')) print("Hello!") ``` If we try to run this script without having **Titano Boa** installed, we'll encounter an error message as **Titanoboa** is not available. **Let's install Titano Boa globally using pip** ```bash python3.11 -m pip install titano Boa ``` This will install **Titano Boa** for the global Python 3.11 environment. Now we can run our script and we'll see the output: ```bash python3.11 basic_python.py ``` We get the correct output because **Titano Boa** was installed globally in our Python 3.11 environment. **UV's strength lies in its ability to manage dependencies for specific project environments. Let's demonstrate this.** **We'll add Titano Boa to our project environment using UV.** **Add a dependency with UV** ```bash uv add titano Boa ``` This will create a new folder called `venv` in our project directory and automatically add **Titano Boa** to the project environment. **UV will also generate a `uv.lock` file.** This file keeps track of all dependencies for our project. **Run our script with UV** ```bash uv run python basic_python.py ``` This will run our script using the Python version and packages specified in our project environment. We can now switch to different Python versions or add different packages to our project, and UV will ensure that the correct versions are used when running our script. **Using pyproject.toml** ```toml [project] name = "Python-in-updraft-cu" version = "0.1.1.0" description = "Add your description here" readme = "README.md" requires-python = ">=3.11" dependencies = [ "titano Boa>=0.2.4", ] ``` The `pyproject.toml` file acts as a configuration file for our project, defining dependencies and other project-related details. When we used `uv add titano Boa`, UV updated this file to include **Titano Boa** in our dependency section. UV's flexibility allows us to easily switch between different Python versions and environments without the hassle of managing global packages or manually installing dependencies for each project.