how to state type while using map in flutter code example

Example 1: flutter get key from map

String key = values.keys.elementAt(index);

Example 2: flutter create new map

Map<String, int> map1 = {'zero': 0, 'one': 1, 'two': 2};
Map map2 = {'zero': 0, 'I': 'one', 10: 'X'};
var map3 = {'zero': 0, 'I': 'one', 10: 'X'};