Added various extensions.

Added coding style helpers.
Unit tests.

SystemExtensions.NetStandard/Extensions/Try.cs

@@ -0,0 +1,69 @@
+using System.Collections.Generic;
+
+namespace System.Extensions
+{
+    public static class Try
+    {
+        public static Try<TResult> Action<TResult>(Func<TResult> act)
+        {
+            return new Try<TResult>(act);
+        }
+    }
+    public class Try<TResult>
+    {
+        private readonly Func<TResult> action;
+        private readonly List<Func<Exception, TResult>> catchActions = new List<Func<Exception, TResult>>();
+        internal Try(Func<TResult> action)
+        {
+            this.action = action;
+        }
+        public static Try<TResult> Action(Func<TResult> act)
+        {
+            return new Try<TResult>(act);
+        }
+
+        public Try<TResult> Catch<TException>(Func<TException, TResult> act) where TException : Exception
+        {
+            this.catchActions.Add((Func<Exception, TResult>)act);
+            return this;
+        }
+
+        public TResult Run()
+        {
+            try
+            {
+                return action();
+            }
+            catch (Exception ex)
+            {
+                foreach (var catchAction in this.catchActions)
+                {
+                    return catchAction(ex);
+                }
+                throw;
+            }
+        }
+
+        public TResult Finally(Action act)
+        {
+            if (act is null) throw new ArgumentNullException(nameof(act));
+
+            try
+            {
+                return this.action();
+            }
+            catch (Exception ex)
+            {
+                foreach (var catchAction in this.catchActions)
+                {
+                    return catchAction(ex);
+                }
+                throw;
+            }
+            finally
+            {
+                act();
+            }
+        }
+    }
+}