class I18n::Locale::Fallbacks

def map(*args, &block)
  if args.count == 1 && !block_given?
    mappings = args.first
    mappings.each do |from, to|
      from, to = from.to_sym, Array(to)
      to.each do |_to|
        @map[from] ||= []
        @map[from] << _to.to_sym
      end
    end
  else
    @map.map(*args, &block)
  end
end