Trying to figure out how to get a single-file python script into NixOS

working-but-ugly.nix

waitUntilConsulValue = pkgs.python36Packages.buildPythonApplication {
  name = "waitUntilConsulValue";
  phases = "installPhase";
  installPhase = ''
    mkdir -p $out/bin
    echo cp ${./waitUntilConsulValue.py} $out/bin/waitUntilConsulValue.py
    cp ${./waitUntilConsulValue.py} $out/bin/waitUntilConsulValue.py

    wrapProgram $out/bin/waitUntilConsulValue.py --prefix PYTHONPATH : "$(toPythonPath ${pkgs.python36Packages.consul})"
  '';
};