anchor.diff:      (enableShared && enableStatic)) then
       "tagged" else "system";
   
  +  cflags = if (enablePIC) then "cflags=-fPIC cxxflags=-fPIC linkflags=-fPIC" else "";
  +
   in
   
   stdenv.mkDerivation {
  
positive.code:   configureScript = "./bootstrap.sh";
    configureFlags = "--with-icu=${icu} --with-python=${python}/bin/python";
  
    buildPhase = "./bjam -sEXPAT_INCLUDE=${expat}/include -sEXPAT_LIBPATH=${expat}/lib --layout=${finalLayout} variant=${variant} threading=${threading} link=${link} install";
  
    installPhase = ":";
  }
  
negative.code: , enableMultiThreaded ? true
  , enableShared ? true
  , enableStatic ? false
  , enablePIC ? false
  }:
  
  let
  