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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 pixel_x_size(self, zoom):
 """ Width of a pixel in SRID units at zoom level. - zoom: zoom level """

        validate_zoom(zoom)
        return round(
            (self.grid.right - self.grid.left) /
            (self.grid.shape.width * 2**zoom * self.tile_size),
            ROUND
        )