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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 reset(self):
 """ Empty board, remove all pieces and reset internal states. """

        # Store positionned pieces on the board.
        self.pieces = set()

        # Squares on the board already occupied by a piece.
        self.occupancy = self.new_vector()

        # Territory susceptible to attacke, i.e. squares reachable by at least
        # a piece.
        self.exposed_territory = self.new_vector()