anchor.diff:  
       # Aliases for the latest Dwarf Fortress and the selected Therapist install
       dwarf-fortress = getAttr (versionToName latestVersion) df-games;
  +    inherit dwarf-therapist-original;
       dwarf-therapist = dwarf-fortress.dwarf-therapist;
       dwarf-fortress-original = dwarf-fortress.dwarf-fortress;
   
  
positive.code: 
          dwarf-therapist = callPackage ./dwarf-therapist/wrapper.nix {
            inherit dwarf-fortress;
            dwarf-therapist = pkgs.qt5.callPackage ./dwarf-therapist {
              texlive = pkgs.texlive.combine {
                inherit (pkgs.texlive) scheme-basic float caption wrapfig adjmulticol sidecap preprint enumitem;
              };
            };
          };
        in
        callPackage ./wrapper {
  
negative.code:   # Converts a version to a package name.
    versionToName = version: "dwarf-fortress_${lib.replaceStrings ["."] ["_"] version}";
  
    dwarf-therapist-original = pkgs.qt5.callPackage ./dwarf-therapist {
      texlive = pkgs.texlive.combine {
        inherit (pkgs.texlive) scheme-basic float caption wrapfig adjmulticol sidecap preprint enumitem;
      };
    };
  
    # A map of names to each Dwarf Fortress package we know about.
    df-games = lib.listToAttrs (map (dfVersion: {
      name = versionToName dfVersion;
  