anchor.diff:  
   python2Packages.buildPythonApplication rec {
     name = "electrum-${version}";
  -  version = "2.7.18";
  +  version = "2.8.1";
   
     src = fetchurl {
       url = "https://download.electrum.org/${version}/Electrum-${version}.tar.gz";
  -    sha256 = "1l9krc7hqhqrm5bwp999bpykkcq4958qwvx8v0l5mxcxw8k7fkab";
  +    sha256 = "1398s9d8j04is24il2xjb6xkj666pj21bsr90xglpsmfa1js9z7g";
     };
   
     propagatedBuildInputs = with python2Packages; [
  
positive.code:   postInstall = ''
      # Despite setting usr_share above, these files are installed under
      # $out/nix ...
      mv $out/lib/python2.7/site-packages/nix/store/*/share $out
      rm -rf $out/lib/python2.7/site-packages/nix
    '';
  
    doInstallCheck = true;
  
negative.code:     jsonrpclib
      pbkdf2
      protobuf3_0
      pyaes
      pycrypto
      pyqt4
      pysocks
      qrcode
      requests
      tlslite
  
      # plugins
      keepkey
      trezor
  
      # TODO plugins
      # amodem
      # btchip
      # matplotlib
    ];
  
    preBuild = ''
  