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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _fast_memory_load_bytes(self, addr, length):
 """ Perform a fast memory loading of some data. :param int addr: Address to read from. :param int length: Size of the string to load. :return: A string or None if the address does not exist. :rtype: bytes or None """


        try:
            return self.project.loader.memory.load(addr, length)
        except KeyError:
            return None