these 3 derivations will be built:
  /nix/store/wg968h9xg745a879ifmzmajcwkjw4iz9-source.drv
  /nix/store/d1fg95qvb7awpzic6vchzamx2wf0kgnk-fx-0.0.16.drv
  /nix/store/jkiircqadqm1l5ciqjpv8isdk17s5ibn-check-fx.drv