Because of typo in the Title (space at the end of the title) the Part 15 of the tutorial is not found under it's planned URL but here.
https://steemit.com/utopian-io/@krischik/using-steem-api-with-ruby-part-15-
Notes:
- I would have deleted and reposted but it's not possible to postings with upvotes¹.
- I also can't change the next “Next tutorial” link in Part 14 any more so this redirection is needed.
¹ Why anyone would upvote in the 15 minutes is beyond me as you don't get curation rewards that way