# File lib/mcollective/rpc/helpers.rb, line 14
      def self.extract_hosts_from_json(json)
        hosts = JSON.parse(json)

        raise "JSON hosts list is not an array" unless hosts.is_a?(Array)

        hosts.map do |host|
          raise "JSON host list is not an array of Hashes" unless host.is_a?(Hash)
          raise "JSON host list does not have senders in it" unless host.include?("sender")

          host["sender"]
        end.uniq
      end