anchor.diff:  { lib
   , buildPythonPackage
  -, fetchPypi
  +, fetchFromGitHub
   , boto3
   , diskcache
   , enum34
  
positive.code:   ] ++ lib.optionals isPy27 [ pathlib enum34 ];
  
    checkInputs = [
      pytest
    ];
  
    # ignore tests which require setup
    checkPhase = ''
      pytest --ignore tests/io_
    '';
  
    meta = with lib; {
      description = "Library to access sliced imaging data";
  
negative.code:   pname = "slicedimage";
    version = "4.1.1";
  
    src = fetchFromGitHub {
      owner = "spacetx";
      repo = pname;
      rev = version;
      sha256 = "1vpg8varvfx0nj6xscdfm7m118hzsfz7qfzn28r9rsfvrhr0dlcw";
    };
  
    propagatedBuildInputs = [
  