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: mod.rs
    path of file: ./repos/boa/core/engine/src/vm/opcode/define
    
    the code of the file until where you have to start completion: use crate::{
    vm::{opcode::Operation, CompletionType},
    Context, JsResult, JsValue,
};

pub(crate) mod class;
pub(crate) mod own_property;

pub(crate) use class::*;
pub(crate) use own_property::*;

/// `DefVar` implements the Opcode Operation for `Opcode::DefVar`
///
/// Operation:
///  - Declare `var` type variable.
#[derive(Debug, Clone, Copy)]
pub(crate) struc
    
    fn operation(context: &mut Context, index: usize) -> JsResult<CompletionType> {
        let value = context.vm.pop();
        let binding_locator = context.vm.frame().code_block.bindings[index].clone();
        context.vm.environments.put_lexical_value(
            binding_locator.environment_index(),
            binding_locator.binding_index(),
            value,
        );

        Ok(CompletionType::Normal)
    }