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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 file_identifier(self):
        # type: () -> bytes
        '''
        A method to get the name of this UDF File Entry as a byte string.

        Parameters:
         None.
        Returns:
         The UDF File Entry as a byte string.
        '''
        if not self._initialized:
            raise pycdlibexception.PyCdlibInternalError('UDF File Entry not initialized')

        if self.file_ident is None:
            return b'/'

        return self.file_ident.fi