mergeWith method
Implementation
Map<K, V> mergeWith(Map<K, V> other, V Function(V a, V b) resolve) {
if (this == null) return other;
final result = Map<K, V>.from(this!);
other.forEach((key, value) {
result[key] = result.containsKey(key)
? resolve(result[key] as V, value)
: value;
});
return result;
}