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: havespace.rs
    path of file: ./repos/mail-server/crates/managesieve/src/op
    
    the code of the file until where you have to start completion: /*
 * Copyright (c) 2020-2022, Stalwart Labs Ltd.
 *
 * This file is part of Stalwart Mail Server.
 *
 * This program is free software: you can redistribute it and/or modify
 *
    
    pub async fn handle_havespace(&mut self, request: Request<Command>) -> crate::op::OpResult {
        let mut tokens = request.tokens.into_iter();
        let name = tokens
            .next()
            .and_then(|s| s.unwrap_string().ok())
            .ok_or_else(|| StatusResponse::no("Expected script name as a parameter."))?;
        let size: usize = tokens
            .next()
            .and_then(|s| s.unwrap_string().ok())
            .ok_or_else(|| StatusResponse::no("Expected script size as a parameter."))?
            .parse::<usize>()
            .map_err(|_| StatusResponse::no("Invalid size parameter."))?;

        // Validate name
        let access_token = self.state.access_token();
        let account_id = access_token.primary_id();
        self.validate_name(account_id, &name).await?;

        // Validate quota
        if access_token.quota == 0
            || size as i64 + self.jmap.get_used_quota(account_id).await?
                <= access_token.quota as i64
        {
            Ok(StatusResponse::ok("").into_bytes())
        } else {
            Err(StatusResponse::no("Quota exceeded.").with_code(ResponseCode::QuotaMaxSize))
        }
    }