class dart code

sample.dart

  // A person. The implicit interface contains greet().
class Person {
  // In the interface, but visible only in this library.
  final String _name;

  // Not in the interface, since this is a constructor.
  Person(this._name);

  // In the interface.
  String greet(String who) => 'Hello, $who. I am $_name.';
}

// An implementation of the Person interface.
class Impostor implements Person {
  String get _name => '';

  String greet(String who) => 'Hi $who. Do you know who I am?';
}

//function that returns a string
String greetBob(Person person) => person.greet('Bob');

class Car {
  final String _name;
  
  Car(this._name);
  
  String horn() => 'Hoooorn! $_name is passing';
}

String greet(Person person, String secondPerson) => person.greet(secondPerson);

void main() {
  
  print(greetBob(Person('Kathy')));
  //   print(Person('James Bond').greet('007'));
  
  print(greetBob(Impostor()));
  
//   print(greetBob(Car('Toyota')));
  
  var human = new Person('Udeme');
//   print(human.greet('Ben'));
  
  print(greet(human, 'Katty'));
  

}