anchor.diff:    preConfigure = ''
       export NO_CUDA=1
     '';
  -  
  +
     meta = {
       description = "Tensors and Dynamic neural networks in Python with strong GPU acceleration.";
       homepage = http://pytorch.org/;
  
positive.code:      git
       numpy.blas
    ];
    
    propagatedBuildInputs = [
      cffi
      numpy
  
negative.code:     owner  = "pytorch";
      repo   = "pytorch";
      rev    = "v${version}";
      sha256 = "1s3f46ga1f4lfrcj3lpvvhgkdr1pi8i2hjd9xj9qiz3a9vh2sj4n";
    };
  
    checkPhase = ''
  