code: function listTopics(next, done) {
      let params = next? {NextToken:next} : {}
      sns.listTopics(params, function _listTopics(err, result) {
        if (err) {
          done(err)
        }
        else {
          // keep track of our current iteration
          let index = 0
          let tidy = t=> t.TopicArn.split(':').reverse().shift()
          // iterate the topics seeking our name
          result.Topics.map(tidy).forEach(t=> {
            if (t === name) {
              found = result.Topics[index].TopicArn
            }
            index += 1
          })
          // if there are more pages walk those
          let more = result.NextToken && !found
          if (more) {
            listTopics(result.NextToken, done)
          }
          else {
            // otherwise we're done walking
            done()
          }
        }
      })
    }
docs: aws-sdk isn't the friendliest api we need to recurse thru topics searching for the arn