Set the desired columns width

        - the elements of the array should be integers, specifying the
          width of each column. For example:

                [10, 20, 5]

def set_cols_width(self, array):
        """Set the desired columns width

        - the elements of the array should be integers, specifying the
          width of each column. For example:

                [10, 20, 5]
        """

        self._check_row_size(array)
        try:
            array = map(int, array)
            if reduce(min, array) <= 0:
                raise ValueError
        except ValueError:
            sys.stderr.write("Wrong argument in column width specification\n")
            raise
        self._width = array