Makes sure the table with the full name comprising of name_seq exists.

def _array_make_sure_table_exists(self, array_name, index, name_seq):
        """
        Makes sure the table with the full name comprising of name_seq exists.
        """
        t = self[array_name][index]
        for key in name_seq[:-1]:
            t = t[key]
        name = name_seq[-1]
        if name not in t:
            new_table = element_factory.create_table({})
            self.append_elements([element_factory.create_table_header_element((array_name,) + name_seq), new_table])
            return new_table