anchor.diff:  
   buildPythonPackage rec {
     pname = "pre-commit-hooks";
  -  version = "3.4.0";
  -  disabled = isPy27;
  +  version = "4.0.1";
  +  disabled = pythonOlder "3.6";
   
  -  # fetchPypi does not provide tests
     src = fetchFromGitHub {
       owner = "pre-commit";
       repo = pname;
       rev = "v${version}";
  -    sha256 = "1aqkmprdc2lhds9c59pkkf2js65j63197flanaggk7cm8k0kz7zs";
  +    sha256 = "sha256-Rg2I79r0Pp3AUgT6mD+kEdm+5CEGgdmFn6G3xcU6fnk=";
     };
   
  -  propagatedBuildInputs = [ toml ruamel_yaml ];
  -  checkInputs = [ git pytestCheckHook ];
  +  propagatedBuildInputs = [
  +    ruamel_yaml
  +    toml
  +  ];
  +
  +  checkInputs = [
  +    git
  +    pytestCheckHook
  +  ];
   
     # the tests require a functional git installation which requires a valid HOME
     # directory.
  
positive.code:     git config --global user.email "nix-builder@nixos.org"
    '';
  
    meta = with lib; {
      description = "Some out-of-the-box hooks for pre-commit";
      homepage = "https://github.com/pre-commit/pre-commit-hooks";
  
negative.code: { lib
  , buildPythonPackage
  , fetchFromGitHub
  , git
  , pythonOlder
  , pytestCheckHook
  , ruamel_yaml
  , toml
  