ast_for_while_stmt(struct compiling *c, const node *n)
{
    /* while_stmt: 'while' test ':' suite ['else' ':' suite] */
    REQ(n, while_stmt);
    int end_lineno, end_col_offset;

    if (NCH(n) == 4) {
        expr_ty expression;
        asdl_seq *suite_seq;

        expression = ast_for_expr(c, CHILD(n, 1));
        if (!expression)
            return NULL;
        suite_seq = ast_for_suite(c, CHILD(n, 3));
        if (!suite_seq)
            return NULL;
        get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
        return While(expression, suite_seq, NULL, LINENO(n), n->n_col_offset,
                     end_lineno, end_col_offset, c->c_arena);
    }
    else if (NCH(n) == 7) {
        expr_ty expression;
        asdl_seq *seq1, *seq2;

        expression = ast_for_expr(c, CHILD(n, 1));
        if (!expression)
            return NULL;
        seq1 = ast_for_suite(c, CHILD(n, 3));
        if (!seq1)
            return NULL;
        seq2 = ast_for_suite(c, CHILD(n, 6));
        if (!seq2)
            return NULL;
        get_last_end_pos(seq2, &end_lineno, &end_col_offset);

        return While(expression, seq1, seq2, LINENO(n), n->n_col_offset,
                     end_lineno, end_col_offset, c->c_arena);
    }

    PyErr_Format(PyExc_SystemError,
                 "wrong number of tokens for 'while' statement: %d",
                 NCH(n));
    return NULL;
}
Unknown