instruction: Write Go code to go by example: regular expressions
output: ```dockerfile
  $ go run regular-expressions.go
  true
  true
  peach
  idx: [0 5]
  [peach ea]
  [0 5 1 3]
  [peach punch pinch]
  all: [[0 5 1 3] [6 11 7 9] [12 17 13 15]]
  [peach punch]
  true
  regexp: p([a-z]+)ch
  a <fruit>
  a PEACH
  ```