'Breakes the conflict between two properties. If either of them
is a default value returns the good one.
If neither returns the default value.
If conflicting returns a tuple with the values'

def propertyTieBreaker(self, key, prop1, prop2):

    if (prop1 in self.defaultValues()):
        return prop2
    elif (prop2 in self.defaultValues()):
        return prop1
    elif self.tieBreakable(key):
        return self.tieBreak(key, prop1, prop2)
    else:
        return (prop1, prop2)
