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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 new(self, length, blocknum):
        # type: (int, int) -> None
        '''
        A method to create a new UDF Long AD.

        Parameters:
         None.
        Returns:
         Nothing.
        '''
        if self._initialized:
            raise pycdlibexception.PyCdlibInternalError('UDF Long AD already initialized')

        self.extent_length = length
        self.log_block_num = blocknum
        self.part_ref_num = 0  # FIXME: we should let the user set this
        self.impl_use = b'\x00' * 6

        self._initialized = True