'Compile into a simple TermGraph with no extra row metadata.
Parameters
screen_name : str
Name to supply for self.screen.
default_screen : zipline.pipeline.term.Term
Term to use as a screen if self.screen is None.'

def to_simple_graph(self, screen_name, default_screen):

    return TermGraph(self._prepare_graph_terms(screen_name, default_screen))
