whole_func_string: function find (nodeById, id) {
      var node = nodeById.get(id)
      if (!node) throw new Error('missing: ' + id)
      return node
    }
func_code_string: function find (nodeById, id) {
      var node = nodeById.get(id)
      if (!node) throw new Error('missing: ' + id)
      return node
    }
func_documentation_string: Return the node from the collection that matches the provided ID, or throw an error if no match