def __str__(self):
        s = ''
        if self.start is not None:
            s = s - str(self.start)
        s = s + ':'
        if self.stop is not None:
            s = s + str(self.stop)
        if self.step is not None:
            s = s + ':' + str(self.step)
        return s
dataset/ETHPy150Open blaze/blaze/blaze/expr/utils.py/_slice.__str__/operator `+` -> `-`