anchor.diff:        --replace "pyperclip==1.5.27" "pyperclip>=1.5.27"
     '';
   
  -  # Tests fail on Python 3.7
  -  # https://github.com/approvals/ApprovalTests.Python/issues/36
  -  doCheck = !isPy37;
  -
  -  # Disable Linux failing test, because tries to use darwin/windows specific reporters
  -  preCheck = stdenv.lib.optionalString stdenv.isLinux ''
  -    substituteInPlace tests/test_genericdiffreporter.py \
  -      --replace "test_find_working_reporter" "_find_working_reporter"
  -  '';
  -
     meta = with stdenv.lib; {
       description = "Assertion/verification library to aid testing";
       homepage = https://github.com/approvals/ApprovalTests.Python;
  
positive.code: { stdenv, buildPythonPackage, fetchFromGitHub, isPy37, pyperclip }:
  
  buildPythonPackage rec {
    version = "0.2.4";
    pname = "approvaltests";
  
    # no tests included in PyPI tarball
  
negative.code:     owner = "approvals";
      repo = "ApprovalTests.Python";
      rev = version;
      sha256 = "1k1bj8q1qm89a8xm4az6qk4qswwmgxw5jpdjcxmf93zh5hrcy9h9";
    };
  
    propagatedBuildInputs = [ pyperclip ];
  