anchor.diff:      rev = "v${version}";
       sha256 = "1w3biv2za2m1brwjy0z049c2m94gm1zfwxzgc6lwrsci724jv9fr";
     };
  -
  -  disable = pythonOlder "3.6";
   
     patches = [
       (fetchpatch {
  
positive.code:     promise
    ];
  
    checkPhase = "black --check graphql_server tests";
  
    checkInputs = [
      black
    ];
  
    meta = with lib; {
      description = "Core package for using GraphQL in a custom server easily";
      homepage = "https://github.com/graphql-python/graphql-server-core";
      license = licenses.mit;
      maintainers = with maintainers; [
        kamadorueda
      ];
    };
  }
  
negative.code: { buildPythonPackage
  , fetchFromGitHub
  , lib
  , graphql-core
  , promise
  , fetchpatch
  , pythonOlder
  , pytestCheckHook
  }:
  
  buildPythonPackage rec {
    pname = "graphql-server-core";
    version = "2.0.0";
    disable = pythonOlder "3.6";
  
    src = fetchFromGitHub {
      owner = "graphql-python";
  