---
MatchData (message='My MatchData with named captures'):
  MatchData#size: 3
  MatchData#regexp: !ruby/regexp /(?<x>.)(?<y>.)?/
  MatchData#to_a:
  - a
  - a
  - 
  MatchData#captures:
  - a
  - 
  MatchData#names:
  - x
  - y