these 3 derivations will be built:
  /nix/store/1xsandsd3xa2f9sgfaiqkbzh3659j69b-cpa-usage-keeper-frontend-1.15.8.drv
  /nix/store/2jmrdmsmarmh55pxg6n2hgcdbfhrm47l-cpa-usage-keeper-1.15.8.drv
  /nix/store/0sjrcsdq0f5ki5m8dvyb3d57ixv5dg6k-check-cpa-usage-keeper.drv