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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 verticals(self):
 """ All vertical squares from the piece's point of view. Returns a list of relative movements up to the board's bound. """

        vertical_shifts = set(izip_longest([], map(
            lambda i: i - self.y, range(self.board.height)), fillvalue=0))
        vertical_shifts.discard((0, 0))
        return vertical_shifts