Add regions to 11.1

Author: BenjaminMichaelis

src/Chapter11/Listing11.01.ThrowingAnException.cs

@@ -1,7 +1,6 @@
 namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter11.Listing11_01
 {
     using System;
-
     #region INCLUDE
     public sealed class TextNumberParser
     {
@@ -11,34 +10,31 @@ public static int Parse(string textDigit)
                 { "zero", "one", "two", "three", "four", 
                   "five", "six", "seven", "eight", "nine" };
 
-    #if !PRECSHARP7
-            int result = Array.IndexOf(
-                digitTexts,
-                // Leveraging C# 2.0’s null-coalescing operator
-                (textDigit ??
-                  // Leveraging C# 7.0’s throw expression
-                  throw new ArgumentNullException(nameof(textDigit))
-                ).ToLower());
-    #else
-            if(textDigit == null) throw new ArgumentNullException(nameof(textDigit))
+            #region EXCLUDE
+            //int result = Array.IndexOf(
+            //    digitTexts,
+            //    // Leveraging C# 2.0’s null-coalescing operator
+            //    (textDigit ??
+            //      // Leveraging C# 7.0’s throw expression
+            //      throw new ArgumentNullException(nameof(textDigit))
+            //    ).ToLower());
+            #endregion EXCLUDE
+
+            if (textDigit == null) throw new ArgumentNullException(nameof(textDigit))
             int result = Array.IndexOf(
                 digitTexts, textDigit?.ToLower());
-    #endif
 
             if (result < 0)
             {
-    #if !PRECSHARP6
-                // Leveraging C# 6.0's nameof operator
-                throw new ArgumentException(
-                    "The argument did not represent a digit", nameof(textDigit));
-    #else
+                #region HIGHLIGHT
                 throw new ArgumentException(
                     "The argument did not represent a digit",
                     "textDigit");
-    #endif
+                #endregion HIGHLIGHT
             }
 
             return result;
         }
     }
+    #endregion INCLUDE
 }