class CommunityVarCollector implements VoidCommunitySetExprVisitor {

  public static @Nonnull Set<CommunityVar> collectCommunityVars(
      @Nonnull Configuration configuration, @Nonnull CommunitySetExpr communitySetExpr) {
    CommunityVarCollector visitor = new CommunityVarCollector(configuration);
    communitySetExpr.accept(visitor);
    return visitor._builder.build();
  }

  private  CommunityVarCollector(@Nonnull Configuration configuration);

}