Can you explain what the concept of Extension in Dart language means and how it is applied?

In Dart, the concept of Extension allows adding new methods and properties to existing classes without the need for inheritance or modifying the original class code.

This is convenient when you need to extend the functionality of classes from third-party libraries or built-in types.

Example of using extension:

extension StringExtensions on String {
  bool get isPalindrome {
    String reversed = split('').reversed.join('');
    return this == reversed;
  }
}

void main() {
  String word = "level";
  print(word.isPalindrome); // true
}

Here, we added a new property isPalindrome to the String class, which checks whether the string is a palindrome. Thus, extensions improve code readability and convenience without changing the original classes.