def hosts
      @hosts ||= begin
        r, h, u = [], (config[:hosts] rescue nil), (config[:user] rescue nil)
        h.each {|host| r << Host.new(host, u) } if h && u; r
      end
    end
def hosts
      @hosts ||= begin
        r, h, u = [], (config[:hosts] rescue nil), (config[:user] rescue nil)
        h.each {|host| r << Host.new(host, u) } if h && u; r
      end
    end
returns an array of host objects