Removing unused usings.

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Aggregates.cs

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Linq;
-using System.Reactive.Disposables;
 
 namespace System.Reactive.Linq
 {

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Awaiter.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information. 
 
-using System;
 using System.Threading;
 using System.Reactive.Disposables;
 using System.Reactive.Subjects;

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Blocking.cs

@@ -2,10 +2,8 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information. 
 
-using System.Collections;
 using System.Collections.Generic;
 using System.Threading;
-using System.Reactive.Disposables;
 
 namespace System.Reactive.Linq
 {

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Concurrency.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information. 
 
 using System.Reactive.Concurrency;
-using System.Reactive.Disposables;
 using System.Threading;
 
 namespace System.Reactive.Linq

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Multiple.cs

@@ -2,13 +2,9 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information. 
 
-using System.Collections;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Linq;
 using System.Reactive.Concurrency;
-using System.Reactive.Disposables;
-using System.Reactive.Subjects;
 using System.Reactive.Threading.Tasks;
 using System.Threading.Tasks;
 

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Single.cs

@@ -5,8 +5,6 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Concurrency;
-using System.Reactive.Disposables;
-using System.Reactive.Subjects;
 
 namespace System.Reactive.Linq
 {