Buf_AddRange
void Buf_AddRange(Buffer *, const char *, const char *);
Buf_AddRange(&buf, items[i].start, items[i].end);
Buf_AddRange(body, *inout_mark, start);
Buf_AddRange(body, *inout_mark, p);
Buf_AddRange(body, mark, end);
Buf_AddRange(&buf, words.words[i].start, words.words[i].end);
Buf_AddRange(res, start, p);