this derivation will be built:
  /nix/store/7h4pqx59lgyln2mdwxcki8p672vrz6pk-interpolate-conformance.drv
bld4: building 7h4pqx59lgyln2mdwxcki8p672vrz6pk-interpolate-conformance.drv
10 cases: Nix interpolate == Python interpolate == expected