anchor.diff:      click
       pytest-benchmark
       pytest-mock
  +    pytest-randomly
       pytest-xdist
  -    sqlite
  -  ];
  +  ] ++ lib.concatMap (name: passthru.extras-require.${name}) testBackends;
   
     preBuild = ''
       # setup.py exists only for developer convenience and is automatically generated
  
positive.code: 
    pythonImportsCheck = [
      "ibis"
    ] ++ (map (backend: "ibis.backends.${backend}") backends);
  
    meta = with lib; {
      description = "Productivity-centric Python Big Data Framework";
  
negative.code:     find "$IBIS_TEST_DATA_DIRECTORY" -type f -exec chmod u+rw {} +
  
      # load data
      for backend in ${lib.concatStringsSep " " testBackends}; do
        ${python.interpreter} ci/datamgr.py load "$backend"
      done
    '';
  