FunctionParameters.dart

import 'package:meta/meta.dart';
int sum(List<int> list, [int initial = 0]) {
 var total = initial;
 list.forEach((v) => total += v);
 return total;
}
String joinToString(List<String> list,
 {@required String separator, String prefix = ", String
suffix = "}) =>
 '$prefix${list.join(separator)}$suffix';
void main() {
 assert(sum([1, 2, 3]) == 6);
 assert(sum([1, 2, 3], 10) == 16);
 assert(joinToString(['a', 'b', 'c'], separator: ',') ==
'a,b,c');
 assert(
 joinToString(['a', 'b', 'c'], separator: '-', prefix:
'*', suffix: '?') ==
 '*a-b-c?');
}