'Clears the plot, removing all curves, markers and tooltips.
Axes and the grid are not removed'

def clear(self):

    for i in self.plot_items():
        if (i is not self.grid_curve):
            self.remove_item(i)
    self.main_curve = None
    self._bounds_cache = {}
    self._transform_cache = {}
    self.clear_markers()
    self.tips.removeAll()
    self.legend().clear()
    self.old_legend_margin = None
    self.update_grid()
