serialize (OpenID::Association)

    # File lib/openid/association.rb, line 64
        def serialize
          data = {
            :version => '2',
            :handle => handle,
            :secret => Util.to_base64(secret),
            :issued => issued.to_i.to_s,
            :lifetime => lifetime.to_i.to_s,
            :assoc_type => assoc_type,
          }

          Util.assert(data.length == FIELD_ORDER.length)

          pairs = FIELD_ORDER.map{|field| [field.to_s, data[field]]}
          return Util.seq_to_kv(pairs, strict=true)
        end