lsearch method
Performs a linear search for key in base.
If not found, it appends key to base.
Implementation
dynamic lsearch(dynamic key, List<dynamic> base, int Function(dynamic, dynamic) compar) {
for (int i = 0; i < base.length; i++) {
if (compar(key, base[i]) == 0) return base[i];
}
base.add(key);
return key;
}