static S dynRenderConcept(O c) {
  if (c == null) ret "null";
  new StringBuilder buf;
  buf.append(c.id + " " + shortDynamicClassName(c));
  for (S field : listFields(c)) {
    O val = cget(c, field);
    if (val != null) {
      buf.append(" " + field + "=");
      buf.append(dynRenderConceptShort(val));
    }
  }
  ret str(buf);
}

static S dynRenderConceptShort(O val) {
  if (val instanceof DynamicObject) {
    O id = getOpt(val, "id");
    if (id instanceof Long)
      ret shortDynamicClassName(val) + id;
  }
  ret struct(val);
}