containsValueNoPurge method
Returns true if any entry currently maps to value.
Same as containsValue, but does NOT purge entries whose key or value
has already been collected. It performs a direct scan and may therefore
temporarily report true for stale keys.
Implementation
bool containsValueNoPurge(Object? value) {
for (var k in _map.keys) {
if (k.payload == value) {
return true;
}
}
return false;
}