dictionary start
dictionary item: a -> [9, 10): []
array start
array item: [10, 11): 1
array item: [13, 14): 2
array item: [16, 17): {}
dictionary start
dictionary item: x -> [22, 25): "y"
container end: [16, 26): {}
array item: [28, 29): 3
array item: [31, 32): {}
dictionary start
dictionary item: keep -> [40, 61): "not in final output"
container end: [31, 62): {
  "keep": "not in final output"
}
container end: [9, 63): []
dictionary item: keep -> [75, 76): []
array start
array item: [76, 77): 1
array item: [79, 83): null
array item: [85, 86): 2
array item: [88, 93): false
array item: [95, 101): "keep"
array item: [103, 104): 3
array item: [106, 107): []
array start
array item: [107, 113): "this"
array item: [115, 121): "keep"
array item: [123, 128): "not"
array item: [130, 137): "final"
container end: [106, 138): [
  "keep"
]
container end: [75, 139): [
  "keep"
]
container end: [0, 141): {
  "keep": [
    "keep"
  ]
}
{
  "keep": [
    "keep"
  ]
}
