Returns table_item's (row, column) cordinates.
        Returns None in case of item not found.

        Args:
            table_item (TableItem): an item instance

def item_coords(self, table_item):
        """Returns table_item's (row, column) cordinates.
        Returns None in case of item not found.

        Args:
            table_item (TableItem): an item instance
        """
        for row_key in self.children.keys():
            for item_key in self.children[row_key].children.keys():
                if self.children[row_key].children[item_key] == table_item:
                    return (int(row_key), int(item_key))
        return None