anchor.diff:  uses
     DUnitX.TestFramework;
   
  +const
  +  CanonicalVersion = '1.4.0';
  +
   type
   
     [TestFixture]
  
positive.code:   assert.AreEqual('', phone.Clean);
  end;
  
  procedure PhoneNumberTests.Invalid_with_right_number_of_digits_but_letters_mixed_in;
  var phone: IPhoneNumber;
  begin
    phone := NewPhoneNumber('1a2b3c4d5e6f7g8h9i0j');
    assert.AreEqual('', phone.Clean);
  end;
  
  procedure PhoneNumberTests.Invalid_if_area_code_does_not_start_with_2_thru_9;
  var phone: IPhoneNumber;
  begin
    phone := NewPhoneNumber('(123) 456-7890');
    assert.AreEqual('', phone.Clean);
  end;
  
  procedure PhoneNumberTests.Invalid_if_exchange_code_does_not_start_with_2_thru_9;
  var phone: IPhoneNumber;
  begin
    phone := NewPhoneNumber('(223) 056-7890');
    assert.AreEqual('', phone.Clean);
  end;
  
  
negative.code: 
      [Test]
      [Ignore]
      procedure Invalid_when_9_digits;
  
      [Test]
      [Ignore]
      procedure Invalid_when_11_digits_does_not_start_with_a_1;
  
      [Test]
      [Ignore]
      procedure Valid_when_11_digits_and_starting_with_1;
  
      [Test]
      [Ignore]
      procedure Valid_when_11_digits_and_starting_with_1_even_with_punctuation;
  
      [Test]
      [Ignore]
  