these 3 derivations will be built:
  /nix/store/3qj3mbp6q93y8z61q6n08bipsli877cv-source.drv
  /nix/store/67h1sd50lgc5v1smrm1hbawv1dgzzm7l-lean-ctx-3.12.3.drv
  /nix/store/6v02ccd092mbg92pgnamhn6fjn9m45y9-check-lean-ctx.drv