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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 open(self, filehandle):
 """Re-open file if necessary."""

        with self.lock:
            if filehandle in self.files:
                self.files[filehandle] += 1
            elif filehandle.closed:
                filehandle.open()
                self.files[filehandle] = 1
                self.past.append(filehandle)