public void RemoveShare(Guid userId, Guid watchlistId, string symbol) { Validate.NotEmpty(userId, nameof(userId)); Validate.NotEmpty(watchlistId, nameof(watchlistId)); Validate.NotNullOrWhitespace(symbol, nameof(symbol)); Watchlist watchlist = GetWatchlist(userId, watchlistId); watchlist.RemoveShare(symbol); _watchlistRepository.Save(watchlist); }