In preparation for a new version of Exercism topics will play a crucial role, so it's very important to have them for each exercise. They should be relevant to the exercise even though you might be able to solve it without encountering that topic. Here is the list of commonly used topics in every track - https://github.com/exercism/problem-specifications/blob/master/TOPICS.txt, please use topics from this list or add one if you think it's missing but required.

There are some exercises which have topics in config.json, so you can look at them as an example.

The full list of affected exercises:

• isogram
• gigasecond
• bob
• run-length-encoding
• meetup
• difference-of-squares
• anagram
• allergies
• series
• robot-simulator
• sieve
• atbash-cipher
• sum-of-multiples
• acronym
• say
• largest-series-product
• kindergarten-garden
• grade-school
• flatten-array
• roman-numerals
• space-age
• grains
• luhn
• etl
• prime-factors
• pig-latin
• simple-cipher
• scrabble-score
• crypto-square
• sublist
• pythagorean-triplet
• circular-buffer
• robot-name
• matrix
• rail-fence-cipher
• nth-prime
• saddle-points
• beer-song
• perfect-numbers
• secret-handshake
• twelve-days
• palindrome-products
• bracket-push
• minesweeper
• queen-attack
• wordy
• phone-number
• ocr-numbers
• house
• triangle
• transpose
• poker
• zebra-puzzle
• rectangles
• binary-search
• list-ops
• book-store
• linked-list
• diamond
• variable-length-quantity
• alphametics
• tournament

Please do NOT create a one single PR to add topics for several exercises, these should be done in separate PRs.

You can see linked issues below and take one