def flatten(self, lst):
if lst == []:<EOL><INDENT>return lst<EOL><DEDENT>if isinstance(lst[<NUM_LIT:0>], list):<EOL><INDENT>return self.flatten(lst[<NUM_LIT:0>]) + self.flatten(lst[<NUM_LIT:1>:])<EOL><DEDENT>return lst[:<NUM_LIT:1>] + self.flatten(lst[<NUM_LIT:1>:])<EOL>
Turn a list of lists into a list.