def clear(self):
        self.ds9.set('regions delete all')
Node instances are always true, even if they're empty.  A node is more
dataset/ETHPy150Open ChrisBeaumont/brut/bubbly/viewer.py/BubblyViewer.clear--crossover with--dataset/ETHPy150Open adieu/allbuttonspressed/docutils/nodes.py/Node.__nonzero__