  The aim of this article is to provide an educational introduction to the
parton shower approach used in particle physics Monte carlo event generators to
simulate radiation via quantum chromodynamics. Following a description of the
fundamental theoretical underpinnings, instructions on how to build a toy
parton shower are given. The associated $\texttt{Python}$ code, along with a
detailed JupyterLab notebook, are publicly available at
https://github.com/apapaefs/pyresias.
