anchor.diff:      freetype
       gdk-pixbuf
       glib
  -    gtk2
  +    gtk3
       libdrm
       libgcrypt
       libnotify
       libpng
       libpulseaudio
  +    libxkbcommon
       mesa
       nss
       pango
  
positive.code: { fetchurl, lib, stdenv, squashfsTools, xorg, alsaLib, makeWrapper, openssl, freetype
  , glib, pango, cairo, atk, gdk-pixbuf, gtk2, cups, nspr, nss, libpng, libnotify
  , libgcrypt, systemd, fontconfig, dbus, expat, ffmpeg_3, curl, zlib, gnome3
  , at-spi2-atk, at-spi2-core, libpulseaudio, libdrm, mesa
  }:
  
  let
  
negative.code:   # If an update breaks things, one of those might have valuable info:
    # https://aur.archlinux.org/packages/spotify/
    # https://community.spotify.com/t5/Desktop-Linux
    version = "1.1.55.494.gca75f788";
    # To get the latest stable revision:
    # curl -H 'X-Ubuntu-Series: 16' 'https://api.snapcraft.io/api/v1/snaps/details/spotify?channel=stable' | jq '.download_url,.version,.last_updated'
    # To get general information:
    # curl -H 'Snap-Device-Series: 16' 'https://api.snapcraft.io/v2/snaps/info/spotify' | jq '.'
    # More examples of api usage:
    # https://github.com/canonical-websites/snapcraft.io/blob/master/webapp/publisher/snaps/views.py
    rev = "45";
  
    deps = [
      alsaLib
  