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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_pushdown(self):
 """Tests whether machine is a pushdown automaton."""

        return (self.num_stores == 3 and
                self.state == 0 and self.has_cell(0) and
                self.input == 1 and self.has_input(1) and
                self.has_stack(2))