these 3 derivations will be built:
  /nix/store/1cs3j7k534fqcyz9dcfx3byyrfaa8x1s-hol_guard-3.9.0.tar.gz.drv
  /nix/store/8w9w147pajib4sjna9bc9xyj2xdqf5s9-hol-guard-3.9.0.drv
  /nix/store/p84g10svkbyp4n5l66lq6rn27br1q4p0-check-hol-guard.drv