         return UnitSpeed.metersPerSecond
     }
     
-    
-    public required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder) }
-    open override func encode(with aCoder: NSCoder) { super.encode(with: aCoder) }
-
     open override func isEqual(_ object: Any?) -> Bool {
         guard let other = object as? UnitSpeed else {
             return false
         }
-
-        if self === other {
-            return true
-        }
-
+        
+        if self === other {
+            return true
+        }
+        
         return super.isEqual(object)
     }
 }

    /*
     Base unit - amperes
     */

    public required init(symbol: String) {
        fatalError("init(symbol:) has not been implemented")
    }

    public required init(symbol: String, converter: UnitConverter) {
        super.init(symbol: symbol, converter: converter)
    }

    private struct Symbol {
        static let megaamperes  = "MA"
        static let kiloamperes  = "kA"

        self.init(symbol: symbol, converter: UnitConverterReciprocal(reciprocal: reciprocal))
    }
    
    open class var litersPer100Kilometers: UnitFuelEfficiency {
        get {
            return UnitFuelEfficiency(symbol: Symbol.litersPer100Kilometers, reciprocal: Coefficient.litersPer100Kilometers)
