map<K, V> static method
Returns a new list where each element of list is transformed by fn. If V is nullable,
and fn returns null, null will be added to the list. Otherwise, use return null to skip these elements.
Call like FP.map<K,V>(fn)(list)
Implementation
static List<V> Function(List<K> list) map<K, V>(V Function(K elem) fn) =>
(final List<K> list) => _map<K, V>(fn, [])(list);