function getList(iterable, keys) {
  if(!Im.Iterable.isIterable(iterable)) {
    return Im.List()
  }
  let val = iterable.getIn(Array.isArray(keys) ? keys : [keys])
  return Im.List.isList(val) ? val : Im.List()
}
Returns an Immutable List, safely
@param {Immutable.Iterable} iterable the iterable to get the key from
@param {String|[String]} key either an array of keys, or a single key
@returns {Immutable.List} either iterable.get(keys) or an empty Immutable.List