'Add a type specific assertEqual style function to compare a type.
This method is for use by TestCase subclasses that need to register
their own type equality functions to provide nicer error messages.
Args:
typeobj: The data type to call this function on when both values
are of the same type in assertEqual().
function: The callable taking two arguments and an optional
msg= argument that raises self.failureException with a
useful error message when the two arguments are not equal.'

def addTypeEqualityFunc(self, typeobj, function):

    self._type_equality_funcs[typeobj] = _AssertWrapper(function)
