class CommunitySetExprEvaluator implements CommunitySetExprVisitor<CommunitySet, CommunityContext> {

  @Override
  public @Nonnull CommunitySet visitCommunitySetReference(
      CommunitySetReference communitySetReference, CommunityContext arg) {
    CommunitySet communitySet = arg.getCommunitySets().get(communitySetReference.getName());
    // conversion to VI should guarantee communitySet is not null
    assert communitySet != null;
    return communitySet;
  }

  private  CommunitySetExprEvaluator();

}