anchor.diff:    createEmptyImage = {size, fullName}: ''
       mkdir $out
       diskImage=$out/disk-image.qcow2
  -    ${kvm}/bin/qemu-img create -f qcow2 $diskImage "${toString size}M"
  +    ${qemu}/bin/qemu-img create -f qcow2 $diskImage "${toString size}M"
   
       mkdir $out/nix-support
       echo "${fullName}" > $out/nix-support/full-name
  
positive.code: 
  rec {
  
    kvm = pkgs.qemu;
  
    qemuProg = "${kvm}/bin/qemu-system-" + (if stdenv.system == "x86_64-linux" then "x86_64" else "i386");
  
  
    modulesClosure = makeModulesClosure {
  
negative.code:     fi
      diskImage="$1"
      if ! test -e "$diskImage"; then
        ${qemu}/bin/qemu-img create -b ${image}/disk-image.qcow2 -f qcow2 "$diskImage"
      fi
      export TMPDIR=$(mktemp -d)
      export out=/dummy
  