Returns the total height of all grid rows

def _get_rows_height(self):
        """Returns the total height of all grid rows"""

        tab = self.grid.current_table
        no_rows = self.grid.code_array.shape[0]
        default_row_height = self.grid.code_array.cell_attributes.\
            default_cell_attributes["row-height"]

        non_standard_row_heights = []
        __row_heights = self.grid.code_array.row_heights
        for __row, __tab in __row_heights:
            if __tab == tab:
                non_standard_row_heights.append(__row_heights[(__row, __tab)])

        rows_height = sum(non_standard_row_heights)
        rows_height += \
            (no_rows - len(non_standard_row_heights)) * default_row_height

        return rows_height