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<b>Warning</b>:  session_start(): open(/var/lib/php/sessions/sess_02f7ccc78qaheok5nk5mi3n92e, 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 />
  A v; // you can access this directly if you use one thread
  
  public synchronized void set(A a) {
    if (v != a) {
      v = a;
      notifyAll();
    }
  }
  
  public synchronized A get() { ret v; }
  public synchronized bool has() { ret v != null; }
  public synchronized void clear() { v = null; }
  
  toString { ret str(this.get()); }