anchor.diff:  
     src = with lib.versions; fetchurl {
       url = "https://www.open-mpi.org/software/ompi/v${major version}.${minor version}/downloads/${pname}-${version}.tar.bz2";
  -    sha256 = "sha256-c4Zvt3CQgZtqjIXLhTljjTfWh3RVglt04onWR6Of1bU=";
  +    sha256 = "1nkwq123vvmggcay48snm9qqmrh0bdzpln0l1jnp26niidvplkz2";
     };
   
     postPatch = ''
  
positive.code: { lib, stdenv, fetchurl, fetchpatch, gfortran, perl, libnl
  , rdma-core, zlib, numactl, libevent, hwloc, targetPackages, symlinkJoin
  , libpsm2, libfabric, pmix, ucx
  
  
negative.code: assert !cudaSupport || cudatoolkit != null;
  
  let
    version = "4.1.1";
  
    cudatoolkit_joined = symlinkJoin {
      name = "${cudatoolkit.name}-unsplit";
  