anchor.diff:  , pybind11
   , pyfma
   , eigen
  -, pytest
  +, pytestCheckHook
   , matplotlib
  -, perfplot
   , isPy27
   }:
   
  
positive.code:   ];
  
    checkInputs = [
      pytest
      matplotlib
      perfplot
    ];
  
    postConfigure = ''
  
negative.code:     export HOME=$(mktemp -d)
    '';
  
    # performance tests aren't useful to us and disabling them allows us to
    # decouple ourselves from an unnecessary build dep
    preCheck = ''
      for f in test/test*.py ; do
        substituteInPlace $f --replace 'import perfplot' ""
      done
    '';
    disabledTests = [ "test_speed_comparison1" "test_speed_comparison2" ];
    pythonImportsCheck = [ "accupy" ];
  
    meta = with lib; {
      description = "Accurate sums and dot products for Python";
  