anchor.diff: -{ lib, buildPythonPackage, fetchFromGitHub
  +{ lib
  +, buildPythonPackage
  +, fetchFromGitHub
   , cython
  -, enum34
   , glibcLocales
   , matplotlib
   , monty
  
positive.code:     requests
      ruamel-yaml
      scipy
      six
      spglib
      sympy
      tabulate
      uncertainties
    ];
  
    # No tests in pypi tarball.
    doCheck = false;
    pythonImportsCheck = [ "pymatgen" ];
  
    meta = with lib; {
      description = "A robust materials analysis code that defines core object representations for structures and molecules";
  
negative.code: 
  buildPythonPackage rec {
    pname = "pymatgen";
    version = "2022.3.29";
    format = "setuptools";
  
    disabled = pythonOlder "3.8";
  
    src = fetchFromGitHub {
      owner = "materialsproject";
      repo = "pymatgen";
      rev= "v${version}";
      hash = "sha256-B2piRWx9TfKlGTPOAAGsq2GxyfHIRBVFpk6dxES0WF0=";
    };
  
    nativeBuildInputs = [
  