How can I reference the `escapeSystemdPath` function (from nixpkgs' `nixos/lib/utils.nix`) in my config?

I want to call the escapeSystemdPath (defined in nixpgs at nixos/lib/utils.nix) to derive the name of a systemd mount unit from the target path (eg. srv-my-dir.mount from /srv/my/dir), but I can't figure out how I can reference it... any ideas?