anchor.diff:  , gtk3
   , wrapGAppsHook
   , glib
  -, amtk
   , appstream-glib
   , gobject-introspection
   , python3
  +, gi-docgen
   , webkitgtk
   , gettext
   , itstool
  
positive.code:     appstream-glib
      gobject-introspection
      python3
    ];
  
    buildInputs = [
      glib
      gtk3
      webkitgtk
      amtk
      gnome.adwaita-icon-theme
      gsettings-desktop-schemas
    ];
  
    doCheck = true;
  
    postPatch = ''
      chmod +x meson_post_install.py # patchShebangs requires executable file
      patchShebangs meson_post_install.py
    '';
  
    preFixup = ''
  
negative.code:       # https://gitlab.gnome.org/GNOME/devhelp/issues/14
        --prefix XDG_DATA_DIRS : "${shared-mime-info}/share"
      )
    '';
  
    postFixup = ''
      # Cannot be in postInstall, otherwise _multioutDocs hook in preFixup will move right back.
      moveToOutput share/doc/devhelp-3 "$devdoc"
    '';
  
    passthru = {
  