Remove unused using statements
MODIFY
src/Chapter07/Listing07.14.SpecifyingWhichBaseConstructorToInvoke.cs
src/Chapter07/Listing07.14.SpecifyingWhichBaseConstructorToInvoke.cs
-using System;
using System.Diagnostics.CodeAnalysis;
namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter07.Listing07_14;

MODIFY
src/Chapter07/Listing07.19.IsOperatorDeterminingTheUnderlyingType.cs
src/Chapter07/Listing07.19.IsOperatorDeterminingTheUnderlyingType.cs
-using System;
-
namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter07.Listing07_19;
public class Program

MODIFY
src/Chapter07/Listing07.20.TuplePatternMatching.cs
src/Chapter07/Listing07.20.TuplePatternMatching.cs
-using System;
-
namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter07.Listing07_20;
using System.IO;

MODIFY
src/Chapter07/Listing07.21.PositionalPatternMatching.cs
src/Chapter07/Listing07.21.PositionalPatternMatching.cs
-using System;
-
namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter07.Listing07_21;
#region INCLUDE

MODIFY
src/Chapter07/Listing07.22.PropertyPatternMatching.cs
src/Chapter07/Listing07.22.PropertyPatternMatching.cs
-using System;
-
namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter07.Listing07_22;
public class Person

MODIFY
src/Chapter07/Listing07.23.RecursivePatternMatching.cs
src/Chapter07/Listing07.23.RecursivePatternMatching.cs
-using System;
-
namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter07.Listing07_23;
public class Person

MODIFY
src/Chapter07/Listing07.24.SwitchWithPatternMatching.cs
src/Chapter07/Listing07.24.SwitchWithPatternMatching.cs
-using System;
-
namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter07.Listing07_24;
public class Program

Remove unused using statements