The horizontal lines that run accross the chart from the x-ticks.

        If a boolean value is given, these gridlines will be turned on or off.
        Otherwise, the method will return their current state.

        :param bool grid: Turns the gridlines on or off.
        :rtype: ``bool``

def x_grid(self, grid=None):
        """The horizontal lines that run accross the chart from the x-ticks.

        If a boolean value is given, these gridlines will be turned on or off.
        Otherwise, the method will return their current state.

        :param bool grid: Turns the gridlines on or off.
        :rtype: ``bool``"""

        if grid is None:
            return self._x_grid
        else:
            if not isinstance(grid, bool):
                raise TypeError("grid must be boolean, not '%s'" % grid)
            self._x_grid = grid