anchor.diff:  -export([init/0, get_number_of_vms/0, add_vms/1, remove_vms/1, killall_vms/0]).
   
   -define(cloud_ssh_key, "2a42cb863313526fca96098a95020db2a904b01157f191a9bb3200829f8596c7").
  --define(scalaris_start, "bin/./scalarisctl -e -detached -s -p 14915 -y 8000 -n node start").
  --define(scalaris_stop, "bin/./scalarisctl -n node gstop").
  +-define(scalaris_start, "bin/./scalarisctl -e -detached -s -p 14915 -y 8000 -n node1 start").
  +-define(scalaris_stop, "bin/./scalarisctl -n node1 gstop").
   
   -type status() :: active | inactive.
   -type host() :: tuple(string(), status()).
  
positive.code:         {_, active} ->
              add_or_remove_vms(add, Pending, RemainingHosts, UpdatedHosts ++ [Host]);
          {Hostname, _} ->
              start_scalaris_vm(Hostname),
              add_or_remove_vms(add, Pending - 1, RemainingHosts, UpdatedHosts ++ [{Hostname, active}])
      end;
  add_or_remove_vms(remove, Pending, Hosts, UpdatedHosts) ->
      [Host | RemainingHosts] = Hosts,
      case Host of
          {Hostname, active} ->
              stop_scalaris_vm(Hostname),
              add_or_remove_vms(remove, Pending - 1, RemainingHosts, UpdatedHosts ++ [{Hostname, inactive}]);
          {_, _} ->
              add_or_remove_vms(remove, Pending, RemainingHosts, UpdatedHosts ++ [Host])
  
negative.code: %%        {autoscale_cloud_module, cloud_ssh}
  %%      The following options can also be set:
  %%        {cloud_ssh_hosts, ["host1", "host2", ..., "hostn"]}.
  %%        {cloud_ssh_path, "path/to/scalaris/installation/on/host"}.
  %%      Additional services besides Scalaris may be specified:
  %%        {cloud_ssh_services, [{ServiceStartCmd, ServiceStopCmd}, {Service2StartCmd, Service2StopCmd}, ...]}.
  