mojo/public/tools/mojom/version_compatibility_unittest.py
def testNewStructFieldNullableReference(self):
    """Adding a new nullable reference-typed field is fine if versioned
    properly."""
    self.assertBackwardCompatible(
        'struct S { int32 a; };',
        'struct S { int32 a; [MinVersion=1] string? b; };')
Adding a new nullable reference-typed field is fine if versioned
    properly.
Adding a new nullable reference-typed field is fine if versioned
properly.
Adding a new nullable reference - typed field is fine if versioned properly .
def testNewStructFieldNullableReference(self):
    self.assertBackwardCompatible(
        'struct S { int32 a; };',
        'struct S { int32 a; [MinVersion=1] string? b; };')
def testNewStructFieldNullableReference ( self ) : self . assertBackwardCompatible ( 'struct S { int32 a; };' , 'struct S { int32 a; [MinVersion=1] string? b; };' )
Adding a new nullable reference-typed field is fine if versioned
properly.
Adding a new nullable reference - typed field is fine if versioned properly .
"""Adding a new nullable reference-typed field is fine if versioned
    properly."""
self