You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: alt.rs
    path of file: ./repos/skytable/server/src/engine/ql/ddl
    
    the code of the file until where you have to start completion: /*
 * Created on Thu Feb 02 2023
 *
 * This file is a part of Skytable
 * Skytable (formerly known as TerrabaseDB or Skybase) is a free and open-source
 * NoSQL database written by Sayan Nandan ("the Author") with the
 * vision to provide flexibility in data modelling without compromising
 * on performance, queryability or scalability.
 *
 * Copyright (c) 2023, Sayan Nandan <ohsayan@outlook.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/>.
 *
*/

use {
    super::syn::{self, DictFoldState, ExpandedField},
    crate::{
        engine::{
            core::EntityIDRef,
            data::DictGeneric,
            error::{QueryError, QueryResult},
            ql::{
                ast::{QueryData, State},
                le
    
    fn alter_remove<Qd: QueryData<'a>>(state: &mut State<'a, Qd>) -> QueryResult<Self> {
        const DEFAULT_REMOVE_COL_CNT: usize = 4;
        /*
            WARNING: No trailing commas allowed
            <remove> ::= <ident> | <openparen> (<ident> <comma>)*<closeparen>
        */
        if compiler::unlikely(state.exhausted()) {
            return compiler::cold_rerr(QueryError::QLUnexpectedEndOfStatement);
        }

        let r = match state.fw_read() {
            Token::Ident(id) => Box::new([*id]),
            Token![() open] => {
                let mut stop = false;
                let mut cols = Vec::with_capacity(DEFAULT_REMOVE_COL_CNT);
                while state.loop_tt() && !stop {
                    match state.fw_read() {
                        Token::Ident(ref ident) => {
                            cols.push(*ident);
                            let nx_comma = state.cursor_rounded_eq(Token![,]);
                            let nx_close = state.cursor_rounded_eq(Token![() close]);
                            state.poison_if_not(nx_comma | nx_close);
                            stop = nx_close;
                            state.cursor_ahead_if(state.okay());
                        }
                        _ => {
                            state.cursor_back();
                            state.poison();
                            break;
                        }
                    }
                }
                state.poison_if_not(stop);
                if state.okay() {
                    cols.into_boxed_slice()
                } else {
                    return Err(QueryError::QLInvalidSyntax);
                }
            }
            _ => return Err(QueryError::QLInvalidSyntax),
        };
        Ok(Self::Remove(r))
    }