def expand_prefix(self, fieldid, prefix):
        """Yields terms in the given field that start with the given prefix.
        """
        
        fieldid = self.schema.to_number(fieldid)
        for fn, t, _, _ in self.iter_from(fieldid, prefix):
            if fn != fieldid or not t.startswith(prefix):
                return
            yield t
dataset/ETHPy150Open dokipen/whoosh/src/whoosh/reading.py/IndexReader.expand_prefix/original