_self: super:
let lib = super.lib; in
{
  lib = (super.lib or { }) // rec {
    unwords = lib.concatStringsSep " ";
    unlines = lib.concatStringsSep "\n";
    unlinesAttrs = f: as: unlines (lib.mapAttrsToList f as);
    unlinesValues = as: unlines (builtins.attrValues as);
  };
}