Maps

  A Map can be created by

Map<String, String> gifts = const {
  'first': 'paper',
  'second': 'cotton',
  'third': 'leather'
}

var gifts = {
  // Key:    Value
  'first': 'partridge',
  'second': 'turtledoves',
  'fifth': 'golden rings'
};

var gifts = Map();
gifts['first'] = 'partridge';
gifts['second'] = 'turtledoves';
gifts['fifth'] = 'golden rings';

var nobleGases = {
  2: 'helium',
  10: 'neon',
  18: 'argon',
};

var nobleGases = Map();
nobleGases[2] = 'helium';
nobleGases[10] = 'neon';
nobleGases[18] = 'argon';