def create_index(self, columns, name=None):
        self._check_dropped()
        if not name:
            sig = '||'.join(columns)

            # This is a work-around for a bug in <=0.6.1 which would create
            # indexes based on hash() rather than a proper hash.
            key = abs(hash(sig))
            name = 'ix_%s_%s' % (self.table.name, key)
            if name in self.indexes:
                return self.indexes[name]

            key = sha1(sig.encode('utf-8')).hexdigest()[:16]
            name = 'ix_%s_%s' % (self.table.name, key)

        if name in self.indexes:
            return self.indexes[name]
        try:
            self.database._acquire()
            columns = [self.table.c[c] for c in columns]
            idx = Index(name, *columns)
            idx.create(self.database.engine)
        except:
            idx = None
        finally:
            self.database._release()
        self.indexes[name] = idx
        return idx
Provide 2 APIs for images. One at "top_img", "imgs"
dataset/ETHPy150Open pudo/dataset/dataset/persistence/table.py/Table.create_index--crossover with--dataset/ETHPy150Open codelucas/newspaper/newspaper/article.py/Article.set_top_img_no_check