def lookBack(self, string):
        past = self.source_text[len(string) - self.pos:self.pos]
        return past.lower() == string

    # Nested pseudo-class if we are insideRule
    # and the next special character found opens
    # a new block
dataset/ETHPy150Open akalongman/sublimetext-codeformatter/codeformatter/lib/cssbeautifier/__init__.py/Beautifier.lookBack/swapped operands of `-`