anchor.diff:  , curl, libiconv, gmp, zfs, parted, bridge-utils, dmidecode
   , enableXen ? false, xen ? null
   , enableIscsi ? false, openiscsi
  +, enableCeph ? false, ceph
   }:
   
   with stdenv.lib;
  
positive.code:     "--with-storage-zfs"
    ] ++ optionals enableIscsi [
      "--with-storage-iscsi"
    ] ++ optionals stdenv.isDarwin [
      "--with-init-script=none"
    ];
  
negative.code:     xen
    ] ++ optionals enableIscsi [
      openiscsi
    ] ++ optionals enableCeph [
      ceph
    ] ++ optionals stdenv.isDarwin [
      libiconv gmp
    ];
  