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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 _fill_column_holes(self):
        '''
        Same as _fill_row_holes but for columns.
        '''
        for column_index in range(self.start[1], self.end[1]):
            table_column = TableTranspose(self.table)[column_index]
            column_start = table_column[self.start[0]]
            if is_text_cell(column_start):
                self._check_fill_title_column(column_index)