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<b>Warning</b>:  session_start(): open(/var/lib/php/sessions/sess_ig3k3hfi5qplpofrg971o57krd, 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 />
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<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 />
persistable sclass TargetAndActual<A> extends MetaWithChangeListeners {
  settableWithVar A target;
  settableWithVar A actual;
  
  *(A *target, A *actual) {}
  
  toString {
    ret commaCombine(
      target == null ?: "Target: " + target,
      actual == null ?: "Actual: " + actual);
  }
  
  A value() { ret actual; }
  
  bool hasTarget() { ret target != null; }
  
  void set(A actual) { actual(actual); }
}