Explain what a Set data structure is and how it is used

In the Dart language, used in Flutter, the data structure Set represents a collection of unique elements without a specific order.

Main characteristics of Set:

• Stores only unique values — duplicates are automatically ignored.
• Fast search, addition, and removal of elements.
• Does not guarantee the order of elements.

Example of using Set in Flutter/Dart:

void main() {
  Set<String> fruits = {'apple', 'banana', 'orange'};
  fruits.add('banana'); // will not be added, as 'banana' already exists
  fruits.add('grape');

  print(fruits); // Outputs: {apple, banana, orange, grape}

  if (fruits.contains('apple')) {
    print('Fruit apple is in the set');
  }
}

Set is useful when you need to store unique elements and quickly check their presence, for example, for data filtering or storing unique identifiers.