@no('newbytes', 1)
    def index(self, sub, *args):
        pos = self.find(sub, *args)
        if pos == -1:
            raise ValueError('substring not found')
        return pos
Like newstr.find() but raise ValueError when the substring is not
dataset/ETHPy150Open OpenCobolIDE/OpenCobolIDE/open_cobol_ide/extlibs/future/types/newstr.py/newstr.index