Abort in XGROUP if the key is not a stream
streamCG *streamCreateCG(stream *s, char *name, size_t namelen, streamID *id) {
    if (s->cgroups == NULL) s->cgroups = raxNew();
    if (raxFind(s->cgroups,(unsigned char*)name,namelen) != raxNotFound)
        return NULL;

    streamCG *cg = zmalloc(sizeof(*cg));
    cg->pel = raxNew();
    cg->consumers = raxNew();
    cg->last_id = *id;
    raxInsert(s->cgroups,(unsigned char*)name,namelen,cg,NULL);
    return cg;
}

streamCG *streamCreateCG(stream *s, char *name, size_t namelen, streamID *id) {
    if (s->cgroups == NULL) s->cgroups = raxNew();
    if (raxFind(s->cgroups,(unsigned char*)name,namelen) != raxNotFound)
        return NULL;

    streamCG *cg = zmalloc(sizeof(*cg));
    cg->pel = raxNew();
    cg->consumers = raxNew();
    cg->last_id = *id;
    raxInsert(s->cgroups,(unsigned char*)name,namelen,cg,NULL);
    return cg;
}
