a bit o' spruce, from http://play.spruce.cf

spruce.json

{"flavor":"1.13.1","prune":["meta"],"env":["HOME=/home/user"],"cherry_pick":[],"yaml":[{"filename":"file1.yml","contents":"top:\n  orig_key: This is a string attached to a key\n  number: 50\n  array1:\n  - first element\n  - second element\n  - third element\n  map:\n    key1: v1\n    key2: v2\n    key3:\n      subkey1: vv1\n      subkey2: vv2\n      subkey3:\n      - nested element 1\n      - nested element 2\n\n  1: 430.0\n  2: this starts as a string\n  array2:\n  - 1\n  - 2\n  - 3\n  - 4\n  inline_array_merge:\n  - will be overwritten\n  - this: will\n    be: merged\n\n\n\ntop:\n  new_key: this is added\n  orig_key: this is replaced\n  map:\n    key4: added key\n    key1: replaced key\n    key2: ~\n    key3:\n      subkey3:\n      - (( append ))\n      - nested element 3\n  array1:\n  - (( prepend ))\n  - prepend this\n  array2:\n  - over\n  - ridden\n  - array\n  1: You can change types too\n  2:\n    even: drastically\n    to:   from scalars to maps/lists\n  inline_array_merge:\n  - (( inline ))\n  - this has been overwritten\n  - be: overwritten\n    merging: success!\nothertop: you can add new top level keys too\n\n\n\n"}],"skip_eval":false,"fallback_append":false,"go_patch":false,"debug":false,"trace":false}