| using Cysharp.Threading.Tasks.Internal; | 
| using System.Collections.Generic; | 
|   | 
| namespace Cysharp.Threading.Tasks.Linq | 
| { | 
|     public static partial class UniTaskAsyncEnumerable | 
|     { | 
|         public static IUniTaskAsyncEnumerable<TSource> Union<TSource>(this IUniTaskAsyncEnumerable<TSource> first, IUniTaskAsyncEnumerable<TSource> second) | 
|         { | 
|             Error.ThrowArgumentNullException(first, nameof(first)); | 
|             Error.ThrowArgumentNullException(second, nameof(second)); | 
|   | 
|             return Union<TSource>(first, second, EqualityComparer<TSource>.Default); | 
|         } | 
|   | 
|         public static IUniTaskAsyncEnumerable<TSource> Union<TSource>(this IUniTaskAsyncEnumerable<TSource> first, IUniTaskAsyncEnumerable<TSource> second, IEqualityComparer<TSource> comparer) | 
|         { | 
|             Error.ThrowArgumentNullException(first, nameof(first)); | 
|             Error.ThrowArgumentNullException(second, nameof(second)); | 
|             Error.ThrowArgumentNullException(comparer, nameof(comparer)); | 
|   | 
|             // improv without combinate? | 
|             return first.Concat(second).Distinct(comparer); | 
|         } | 
|     } | 
| } |