# File lib/data_objects/uri.rb, line 25
    def to_s
      string = ""
      string << "#{scheme}://"   if scheme
      if user
        string << "#{user}"
        string << ":#{password}" if password
        string << "@"
      end
      string << "#{host}"        if host
      string << ":#{port}"       if port
      string << path.to_s
      if query
        string << "?" << query.map do |key, value|
          "#{key}=#{value}"
        end.join("&")
      end
      string << "##{fragment}"   if fragment
      string
    end