def new_with_value_if_need(klass, value)
      if value.is_a?(klass)
        value
      else
        klass.new(value)
      end
    end
def new_with_value_if_need(klass, value)
      if value.is_a?(klass)
        value
      else
        klass.new(value)
      end
    end
If +value+ is an instance of class +klass+, return it, else
 create a new instance of +klass+ with value +value+.