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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 close(self):
 """ Close all connections and empty the pool. This method is thread safe. """

        if self._closed:
            return
        try:
            with self.lock:
                if not self._closed:
                    self._closed = True
                    for address in list(self.connections):
                        self.remove(address)
        except TypeError as e:
            pass