anchor.diff: -{ lib, fetchPypi, python, buildPythonPackage, gfortran, pytest, blas, writeTextFile, isPyPy }:
  +{ lib
  +, fetchPypi
  +, python
  +, buildPythonPackage
  +, gfortran
  +, pytest
  +, blas
  +, writeTextFile
  +, isPyPy
  +, cython
  +, setuptoolsBuildHook
  + }:
   
   let
     blasImplementation = lib.nameFromURL blas.name "-";
  
positive.code: in buildPythonPackage rec {
    pname = "numpy";
    version = "1.18.0";
  
    src = fetchPypi {
      inherit pname version;
  
negative.code:     sha256 = "a9d72d9abaf65628f0f31bbb573b7d9304e43b1e6bbae43149c17737a42764c4";
    };
  
    nativeBuildInputs = [ gfortran pytest cython setuptoolsBuildHook ];
    buildInputs = [ blas ];
  
    patches = lib.optionals python.hasDistutilsCxxPatch [
  