chore: add C# sample file (#2173)

samples/cs.cs

@@ -0,0 +1,72 @@
+using System;
+// ReSharper disable All
+#pragma warning disable 67
+#pragma warning disable 169
+
+class All(string key)
+{
+  /**
+    * let's C# how it used to be
+    */
+  public delegate void EventHandler(object sender, EventArgs s);
+  public event EventHandler Event;
+
+  private int myField;
+
+  [Obsolete]
+  public All(int field, int property)
+  {
+    myField = field;
+    Property = property;
+  }
+
+  public int Property { get; }
+
+  private int Method(int parameter)
+  {
+    var mutable = Property ^ myField;
+    var usual = 31 * parameter;
+    mutable += usual + 13;
+    return mutable;
+  }
+
+  private static int StaticMethod(int parameter)
+  {
+    unchecked
+    {
+      var usual = 31 * parameter;
+      var sum = 0;
+      var something = new { special = 13 };
+      foreach (var number in new[] {1, 2, 3, 4, 5})
+      {
+        sum += number << 2;
+#if !RELEASE
+        Console.Write($"Trace: {sum} ({something.special})\r\n\r\n");
+#endif
+        Local();
+      }
+
+      void Local()
+      {
+        sum += usual + 13;
+      }
+
+      return sum;
+    }
+  }
+}
+
+public static class Util
+{
+  /// <summary>
+  /// Checks of the properties of <see cref="IComparable"/> objects
+  /// </summary>
+  /// <param name="value">value to be checked</param>
+  /// <typeparam name="T">type of the value</typeparam>
+  /// <returns>true if the property holds</returns>
+  public static bool CheckReflexivity<T>(this T value)
+      where T : IComparable<T>
+  {
+      return value.CompareTo(value) == 0;
+  }
+}