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

spruce.json

{"flavor":"1.29.0","prune":["meta"],"env":["HOME=/home/user","REDACT=''"],"cherry_pick":[],"yaml":[{"filename":"file1.yml","contents":"meta:\n  a: one\n  b: two\n  vp: (( concat meta.a \"/\" meta.b \":key\" )) \n\n\nout:\n  m: (( grab meta ))\n  v1: (( vault meta.a \"/\" meta.b \":key\" ))\n  v2: (( vault meta.vp ))\n  v3: (( vault \"one/two:key\" ))\n  dv1: (( defer vault meta.a \"/\" meta.b \":key\" ))\n  dv2: (( defer vault meta.vp ))\n  dv3: (( defer vault \"one/two:key\" ))\n\n\n\n\n\n"}],"skip_eval":false,"fallback_append":false,"go_patch":false,"debug":true,"trace":false}