anchor.diff:      ++ optional echo "--add-module=${echo-ext}"
       ++ optional ngx_lua "--add-module=${develkit-ext} --add-module=${lua-ext}"
       ++ optional set_misc "--add-module=${set-misc-ext}"
  -    ++ optional (elem stdenv.system (with platforms; linux ++ freebsd)) "--with-file-aio";
  +    ++ optional (elem stdenv.system (with platforms; linux ++ freebsd)) "--with-file-aio"
  +    ++ optional fluent "--add-module=${fluentd}";
   
   
     additionalFlags = optionalString stdenv.isDarwin "-Wno-error=deprecated-declarations -Wno-error=conditional-uninitialized";
  
positive.code:     sha256 = "1bd1isacsiay73nc2jlp0wky32l42a3sjskvfa1082l12g0p1x39";
    };
  
  in
  
  stdenv.mkDerivation rec {
  
negative.code: , echo ? false
  , ngx_lua ? false
  , set_misc ? false
  , fluent ? false
  }:
  
  with stdenv.lib;
  