def define_source(name, url, &block)
      source = Source.new(name, url)
      source.instance_eval(&block)

      @source = source
    end
def define_source(name, url, &block)
      source = Source.new(name, url)
      source.instance_eval(&block)

      @source = source
    end
Define the source to mirror.

 @param [String] name
 @param [String] url
 @param [Proc] block