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: cse.rs
    path of file: ./repos/databend/src/query/sql/src/evaluator
    
    the code of the file until where you have to start completion: // Copyright 2021 Datafuse Labs
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
//
    
fn perform_cse_replacement(expr: &mut Expr, cse_replacements: &HashMap<String, Expr>) {
    // If expr itself is a key in cse_replacements, return the replaced expression.
    if let Some(replacement) = cse_replacements.get(&expr.sql_display()) {
        *expr = replacement.clone();
        return;
    }

    match expr {
        Expr::Cast {
            expr: inner_expr, ..
        } => {
            perform_cse_replacement(inner_expr.as_mut(), cse_replacements);
        }
        Expr::FunctionCall { args, .. } | Expr::LambdaFunctionCall { args, .. } => {
            for arg in args.iter_mut() {
                perform_cse_replacement(arg, cse_replacements);
            }
        }
        // ignore constant and column ref
        Expr::Constant { .. } | Expr::ColumnRef { .. } => {}
    }
}