The book Nonlinear Finite Element Analysis of Solids and Structures 2nd Edition has an associated python code package called pyFEM, but a search for this code finds several others with the same or similar names:

The pyFEM sites associated with the book are:

jjcremmers/PyFEM: A Python finite element code (github.com)

and an associated pypi site:

PyFEM-TUE · PyPI

PyFEM is a python-based finite element code accompanies the book: ‘Non-Linear Finite Element Analysis of Solids and Structures’ by R. de Borst, M.A. Crisfield, J.J.C. Remmers and C.V. Verhoosel. The code is open source and intended for educational and scientific purposes only. If you use PyFEM in your research, the developers would be grateful if you could cite the book in your work.

Another github site of the same name, but apparently entirely independent is:

rvcristiand/pyFEM: Finite Elements Analysis with python (github.com)

A third package of the same name, but with the specific purpose of finite element mesh conversion is:

The PyFEM Mesh Conversion Software Library

The PyFEM library is an open -software project for the conversion of 2D and 3D mesh formats. • Primarily designed for conversion of Finite Element meshes as used in numerical simulations in the geosciences.