anchor.diff:    # Test suite explicitly requires pytest
     checkInputs = [
       pytestCheckHook
  +    pytest-subtests
       numpy
       matplotlib
       uncertainties
  
positive.code:     description = "Physical quantities module";
      license = licenses.bsd3;
      homepage = "https://github.com/hgrecco/pint/";
      maintainers = [ maintainers.costrouc ];
    };
  
  }
  
negative.code: 
  buildPythonPackage rec {
    pname = "pint";
    version = "0.18";
  
    src = fetchPypi {
      inherit version;
      pname = "Pint";
      sha256 = "sha256-jEvOiEwmkFH+t6vGnb/RhAPAx2SryD2hMuinIi+LqAE=";
    };
  
    disabled = pythonOlder "3.6";
  