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<b>Warning</b>:  session_start(): open(/var/lib/php/sessions/sess_bn3vbkfa47podlgjcap41ukdkg, O_RDWR) failed: No space left on device (28) in <b>/var/www/tb-usercake/models/config.php</b> on line <b>51</b><br />
<br />
<b>Warning</b>:  session_start(): Failed to read session data: files (path: /var/lib/php/sessions) in <b>/var/www/tb-usercake/models/config.php</b> on line <b>51</b><br />
// TODO: comparators!?
static MultiMap similarEmptyMultiMap(MultiMap m) {
  if (m cast TreeMultiMap)
    ret new TreeMultiMap(m);
  ret similarEmptyMultiMap(m?.data);
}

static MultiMap similarEmptyMultiMap(Map m) {
  new MultiMap mm;
  if (m != null)
    mm.data = similarEmptyMap(m);
  ret mm;
}