// https://stackoverflow.com/a/38750895
const allowed_fields = ["appear", "vanish", "start", "end"];
const filtered_move = Object.keys(move)
.filter(key => allowed_fields.includes(key))
.reduce((obj, key) => {
// https://stackoverflow.com/a/38750895
const allowed_fields = ["appear", "vanish", "start", "end"];
const filtered_move = Object.keys(move)
.filter(key => allowed_fields.includes(key))
.reduce((obj, key) => {