···754754 sky = throw "sky has been removed from nixpkgs (2020-09-16)";
755755 skype = skypeforlinux; # added 2017-07-27
756756 skype_call_recorder = throw "skype_call_recorder has been removed from nixpkgs, because it stopped working when classic Skype was retired."; # added 2020-10-31
757757+ skype4pidgin = throw "skype4pidgin has been remove from nixpkgs, because it stopped working when classic Skype was retired."; # added 2021-07-14
757758 skydive = throw "skydive has been removed from nixpkgs (2019-09-10)";
758759 slack-dark = slack; # added 2020-03-27
759760 slic3r-prusa3d = prusa-slicer; # added 2019-05-21