def sources= sources = []
      return unless sources.kind_of? Array
      @sources = sources.map{|source| Hashie::Mash.new source }
    end
def sources= sources = []
      return unless sources.kind_of? Array
      @sources = sources.map{|source| Hashie::Mash.new source }
    end
make sure that sources are wrapped as Hashies to allow method access