def set_cols_valign(self, array):
        """Set the desired columns vertical alignment

        - the elements of the array should be either "t", "m" or "b":

            * "t": column aligned on the top of the cell
            * "m": column aligned on the middle of the cell
            * "b": column aligned on the bottom of the cell
        """

        self._check_row_size(array)
        self._valign = array
        return self
Set the desired columns vertical alignment

        - the elements of the array should be either "t", "m" or "b":

            * "t": column aligned on the top of the cell
            * "m": column aligned on the middle of the cell
            * "b": column aligned on the bottom of the cell