these 3 derivations will be built:
  /nix/store/rbj122ycfxn0n73zm652l5szb5kali4f-source.drv
  /nix/store/vxq7v6zfy6b1klmabxxlrvd1fjwgy9vc-fx-0.0.13.drv
  /nix/store/3wxf7yifq9svdxra5wzp2vh5hvz75ffg-check-fx.drv