def previewed_data(hosts, commands)
      @commands = commands
      hosts.map do |each|
        @host_param = each
        # [for a host] operation
        ready_to_open_host_session do |spawn_cmd|
          whole_previewed_parameters(spawn_cmd)
        end
      end
    end
def previewed_data(hosts, commands)
      @commands = commands
      hosts.map do |each|
        @host_param = each
        # [for a host] operation
        ready_to_open_host_session do |spawn_cmd|
          whole_previewed_parameters(spawn_cmd)
        end
      end
    end
Preview all parameters for all hosts (for testing)
 @param [Array<Hash>] hosts Host parameters (read from host list file).
 @param [Array<String>] commands Commands (read from command list file).