public void Action(
     KeyValuePair<int, int> instance)
 {
     int? item = null;
     instance.Let((a, b) => { item = a; });
     Assert.Equal(instance.Key, item);
 }
 public void Second_variable(
     KeyValuePair<int, int> instance)
 {
     Assert.Equal(instance.Value, instance.Let((a, b) => b));
 }
 public void First_variable(
     KeyValuePair<int, int> instance)
 {
     Assert.Equal(instance.Key, instance.Let((a, b) => a));
 }