Gets the set of changed bytes between self and other.

def changed_bytes(self, other):
        """
        Gets the set of changed bytes between self and other.
        """

        changes = set()

        l.warning("FastMemory.changed_bytes(): This implementation is very slow and only for debug purposes.")
        for addr,v in self._contents.items():
            for i in range(self.width):
                other_byte = other.load(addr+i, 1)
                our_byte = v.get_byte(i)
                if other_byte is our_byte:
                    changes.add(addr+i)

        return changes