The total amount of self time in this frame (including self time recorded by SelfTimeFrame
        children)

def total_self_time(self):
        '''
        The total amount of self time in this frame (including self time recorded by SelfTimeFrame
        children)
        '''
        self_time = self.self_time
        for child in self.children:
            if isinstance(child, SelfTimeFrame):
                self_time += child.self_time
        return self_time