@Override
    public Function<T, R> get() {
        return mapper;
    }
@param <T>  input {@code BaseStream} type
@param <R>  output (return) {@code BaseStream} type

@author  Per Minborg
@since   2.1.0
runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/stream/action/Action.java