New way in more detail

• • qr/
  • ^ # Start of string
  • ( # Start capture group 1
  • \( # Open paren
  • (?> # Possessive capture subgroup
  • [^()]++ # Grab all the non parens we can
  • | # or
  • (?1) # Recurse into group 1
  • )* # Zero more times
  • \) # Close Paren
  • ) # End capture group 1
  • $ # End of string
  • /x;