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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 get_column_index(self, header):
 """Get index of a column from it's header. Parameters header: str header of the column. Raises ------ ValueError: If no column could be found corresponding to `header`. """

        try:
            index = self._column_headers.index(header)
            return index
        except ValueError:
            raise_suppressed(KeyError(("'{}' is not a header for any "
                                       "column").format(header)))