anchor.diff:  
     configurePhase = ":";
   
  -  installPhase = with pythonPackages; ''
  +  installPhase = ''
       mkdir -p $out/lib/ycmd/third_party $out/bin
       cp -r ycmd/ CORE_VERSION libclang.so.* ycm_client_support.so ycm_core.so $out/lib/ycmd/
       ln -s $out/lib/ycmd/ycmd/__main__.py $out/bin/ycmd
  
positive.code: 
    buildInputs = [ cmake boost ];
  
    propagatedBuildInputs = with pythonPackages; [ waitress frozendict bottle ];
  
    buildPhase = ''
      export EXTRA_CMAKE_ARGS=-DPATH_TO_LLVM_ROOT=${llvmPackages.clang-unwrapped}
  
negative.code: { stdenv, fetchgit, cmake, llvmPackages, boost, python2Packages
  }:
  
  let
    inherit (python2Packages) python mkPythonDerivation waitress frozendict bottle;
  in mkPythonDerivation rec {
    name = "ycmd-2016-01-12";
    namePrefix = "";
  
  