anchor.diff:      
       needTeensyCores = board.platform == "teensy";
       
  -    targetFile = pkgs.writeText "aprinter-nixbuild.sh" ''
  +    targetFile = writeText "aprinter-nixbuild.sh" ''
           ${stdenv.lib.optionalString isAvr "CUSTOM_AVR_GCC=${gccAvrAtmel}/bin/avr-"}
           ${stdenv.lib.optionalString isArm "CUSTOM_ARM_GCC=${gcc-arm-embedded}/bin/arm-none-eabi-"}
           ${stdenv.lib.optionalString needAsf "CUSTOM_ASF=${asf}"}
  
positive.code:         
          TARGETS+=( "nixbuild" )
          target_nixbuild() {
          ${targetVarsText}
          }
      '';
      
      mainFile = pkgs.writeText "aprinter-main.cpp" mainText;
      
  in
  
  
negative.code:     
      src = stdenv.lib.cleanSource ./..;
      
      configurePhase = ''
          rm config/*
          ln -s ${targetFile} config/nixbuild.sh
  