restrict method

T restrict(
  1. T? item, {
  2. required T orElse,
})

Restricts some item to one of those present in this iterable.

Returns the item itself, if it's present in this iterable. Otherwise, return orElse. For example:

var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31];
primes.restrict(14, orElse: -1); // Returns -1.
primes.restrict(7, orElse: -1); // Returns 7.

Implementation

T restrict(T? item, {required T orElse}) => contains(item) ? item as T : orElse;