const stacks = new Map()

visitParents(tree, (node, parents) => {
  if (nodesToFind.includes(node)) {
    stacks.set(node, parents)
  }
})

nodesToFind.forEach(node => {
  if (!stacks.has(node)) {
    throw new Error('unist-util-ancestor requires all nodes be contained in the tree')
  }
})

// Somethign like this?
let index = -1
let ancestor = tree

// This is broken, maybe you get the gist?
while (++index) {
  const nextAncestor = stacks.get(nodesToFind[0])[index]

  const shared = nodesToFind.every(node => stacks.get(node)[index] === nextAncestor)

  // To do: exit if there are no nodes left on stacks.

  if (shared) {
    ancestor = nextAncestor
  } else {
    break
  }
}