anchor.diff:  { lib
   , stdenv
   , buildPythonPackage
  -, dataclasses
   , fetchFromGitHub
   , hypothesis
   , libiconv
  
positive.code: 
  buildPythonPackage rec {
    pname = "libcst";
    version = "0.4.1";
    format = "pyproject";
  
    disabled = pythonOlder "3.6";
  
    src = fetchFromGitHub {
      owner = "instagram";
      repo = pname;
      rev = "v${version}";
      sha256 = "sha256-soAlt1KBpCn5JxM1b2LZ3vOpBn9HPGdbm+BBYbyEkfE=";
    };
  
    cargoDeps = rustPlatform.fetchCargoTarball {
      inherit src;
      sourceRoot = "source/${cargoRoot}";
      name = "${pname}-${version}";
      hash = "sha256:1rz1c0dv3f1h2m5hwdisl3rbqnmifbva4f0c4vygk7rh1q27l515";
    };
  
    cargoRoot = "native";
  
negative.code:     description = "Concrete Syntax Tree (CST) parser and serializer library for Python";
      homepage = "https://github.com/Instagram/libcst";
      license = with licenses; [ mit asl20 psfl ];
      maintainers = with maintainers; [ SuperSandro2000 ];
    };
  }
  