added IsEmpty method for IEnumerable. Closes #3.

NSupport.Test/EnumerableAccessTest.cs

@@ -76,5 +76,26 @@ public class EnumerableAccessTest {
             Assert.Equal(1, array.Count());
             Assert.Single(array, "a");
         }
+
+        [Fact]
+        public void Test_IsEmpty_with_null_collection() {
+            int[] nullArray = null;
+
+            Assert.Equal(true, nullArray.IsEmpty());
+        }
+
+        [Fact]
+        public void Test_IsEmpty_with_empty_collection() {
+            var emptyCol = Enumerable.Empty<int>();
+
+            Assert.Equal(true, emptyCol.IsEmpty());
+        }
+
+        [Fact]
+        public void Test_IsEmpty_with_non_empty_collection() {
+            var col = new int[] { 1 };
+
+            Assert.Equal(false, col.IsEmpty());
+        }
     }
 }

NSupport/EnumerableAccess.cs

@@ -27,5 +27,15 @@ public static class EnumerableAccess {
         public static IEnumerable<T> To<T>(this IEnumerable<T> source, int index) {
             return source.Take(++index);
         }
+
+        /// <summary>
+        /// Determines whether a sequence is empty.
+        /// </summary>
+        /// <typeparam name="T">The type of the elements of <paramref name="source"/>.</typeparam>
+        /// <param name="source">An <see cref="IEnumerable{T}"/> to check for emptiness.</param>
+        /// <returns>true if the source sequence is null or contains no elements; otherwise, false.</returns>
+        public static bool IsEmpty<T>(this IEnumerable<T> source) {
+            return source == null || !source.Any();
+        }
     }
 }