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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def CompleteBreakpoint(self, breakpoint_id):
 """Marks the specified breaking as completed. Appends the ID to set of completed breakpoints and clears it. Args: breakpoint_id: breakpoint ID to complete. """

    with self._lock:
      self._completed.add(breakpoint_id)
      if breakpoint_id in self._active:
        self._active.pop(breakpoint_id).Clear()