these 2 derivations will be built:
  /nix/store/rqlp3za5sjxf2cs8xx40hb6rjjjgs9ib-iets-0.2.0.drv
  /nix/store/4giqfbcl6v5090hkvjnyfsxy94z4pbv9-iets-classic-2.34.9.drv