const between = require('unist-util-find-all-between')
const u = require('unist-builder')

const parent = u('tree', [
  u('leaf', 'leaf 1'),
  u('node', [u('leaf', 'leaf 2'), u('leaf', 'leaf 3')]),
  u('leaf', 'leaf 4'),
  u('node', [u('leaf', 'leaf 5')]),
  u('leaf', 'leaf 6'),
  u('void'),
  u('leaf', 'leaf 7')
])

const result = between(parent, 0, 4, 'leaf')

console.log(result)

[ { type: 'leaf', value: 'leaf 4' } ]

// ...

const start = {
  type: 'leaf',
  value: 'leaf 4'
}

const end = {
  type: 'leaf',
  value: 'leaf 6'
}

const result = between(parent, start, end, 'node')

console.dir(result, {depth: null})

[ { type: 'node',
    children: [ { type: 'leaf', value: 'leaf 5' } ] } ]