class SystemUser {

  String password;

  SystemUser(String password) {
   this.password = password;
  }

  //new SystemUser( "12345" ).changePassword( "54321" ) -> void
  //   SystemUser( password = "12345" ) -> SystemUser( password = "54321" )
  //To modify this SystemUser's password
  //Note will change this.password
  void changePassword( String newPassword ) {
    // ... this.password ... newPassword ...
    this.password = newPassword;
  }
}