these 3 derivations will be built:
  /nix/store/0kvpm0gdc3j4x228wfq2j48bwn68vllk-cpa-usage-keeper-frontend-2.1.0.drv
  /nix/store/ka9p6lafcngmljfqv3l2sr2g2zmwdxy3-cpa-usage-keeper-2.1.0.drv
  /nix/store/3kjk778anl8gjslqbc49ji8y92zzppfh-check-cpa-usage-keeper.drv