anchor.diff:    src = fetchurl {
       urls = tarballUrls "${version}-${channel}";
       hashOutput = false;
  -    sha256 = "eeb4c6eb2c4021e22d6278cdcd02815470243ed81077be0cbd0f233fa6fc07e8";
  +    sha256 = "e864af41a336bb11dab1a23f32993afe963c1f69618bd9292b89ecf6904845b0";
     };
   
     buildInputs = [
  
positive.code: }:
  
  let
    version = "2.1.9";
    channel = "beta";
  
    tarballUrls = version: [
      "https://github.com/libevent/libevent/releases/download/release-${version}/libevent-${version}.tar.gz"
  
negative.code:     python3  # For event_rpcgen.py
    ];
  
    preConfigure = ''
      prefix="$dev"
      export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $lib/lib"
    '';
  
    configureFlags = [
      "--enable-gcc-hardening"
      "--disable-samples"
    ];
  
    disableStatic = false;
  
    postInstall = ''
      mkdir -p "$lib"/lib
      mv "$dev"/lib/*.so* "$lib"/lib
  
      mkdir -p "$dev"/nix-support
      echo "$lib" >"$dev"/nix-support/propagated-native-build-inputs
    '';
  
    outputs = [
      "dev"
      "lib"
    ];
  
    passthru = {
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "2.1.10-stable";
        inherit (src)
          outputHashAlgo;
        outputHash = "e864af41a336bb11dab1a23f32993afe963c1f69618bd9292b89ecf6904845b0";
        fullOpts = {
          pgpsigUrls = map (n: "${n}.asc") urls;
          pgpKeyFingerprints = [
  