         }
     }
 
+
+    /**
+        validate
+    */
     public func validate(input value: T) throws {
         let iterator = iteratorFactory()
         for next in iterator where next == value {

        throw error(with: sequence)
    }
}

    }
}

/**
    Validate that a sequence contains a given value
*/
public struct Contains<
    T where
    T: Sequence,
