anchor.diff:  
   buildPythonPackage rec {
     pname = "pygls";
  -  version = "0.12";
  +  version = "0.12.1";
     format = "setuptools";
  -  disabled = !isPy3k;
  +
  +  disabled = pythonOlder "3.7";
   
     src = fetchFromGitHub {
       owner = "openlawlibrary";
       repo = pname;
  -    rev = "v${version}";
  -    sha256 = "sha256-PEfGxOUsiZ5WLmoQkOP2RRWJlIKi+42lOu55C3C+k8A=";
  +    rev = "refs/tags/v${version}";
  +    sha256 = "sha256-L2KTNiI+I+r2fF88B1NSunowokrDzGCw3PXbxekg/oE=";
     };
   
     SETUPTOOLS_SCM_PRETEND_VERSION = version;
  
positive.code:     toml
      typeguard
    ];
    # We don't know why an early version of pydantic is required, see:
    # https://github.com/openlawlibrary/pygls/issues/221
    preBuild = ''
      substituteInPlace setup.cfg \
        --replace "pydantic>=1.7,<1.9" "pydantic"
    '';
  
    checkInputs = [
      mock
  
negative.code: { lib
  , buildPythonPackage
  , pythonOlder
  , fetchFromGitHub
  , setuptools-scm
  , pydantic
  