partition function
Implementation
List partition(dynamic list, dynamic iteratee) {
if (list is String) list = list.split('');
return reduce(list, (List<List<dynamic>> result, dynamic value, int index) {
if (evaluatePredicateKey(iteratee, value)) {
result[0].add(value);
} else {
result[1].add(value);
}
return result;
}, [[], []]);
}