operator [] method
Implementation
SafeMap operator [](dynamic key) {
if (value is Map) return SafeMap(value[key]);
if (value is List) return SafeMap(value.asMap()[key]);
return SafeMap(null);
}
SafeMap operator [](dynamic key) {
if (value is Map) return SafeMap(value[key]);
if (value is List) return SafeMap(value.asMap()[key]);
return SafeMap(null);
}