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: simple_frontend.rs
    path of file: ./repos/nickel/core/src/repl
    
    the code of the file until where you have to start completion: //! Simple, UI-agnostic interface to the REPL. Take string inputs and return string outputs.
//! The output may contain ANSI escape codes.
use super::{command::Command, *};
use crate::error::Error;
use crate::{serialize, serialize::ExportFormat};
use std::io::Cursor;

/// Add a failure mode to usual errors for features that are not supported by all REPLs (for
/// example, the `:load` command in the WASM frontend).
pub enum InputError {
    NickelError(Error),
    Other(String),
}

/// The successful result of the evaluation of an input.
pub enum InputResult {
    /// The input succeeded with associated error message.
    Success(String),
    /// The input was blank.
    Blank,
    /// The input is incomplete.
    Partial,
}

impl From<Error> for InputError {
    fn from(error: Error) -> InputError {
        InputError::NickelError(error)
    }
}

/// Return a new instance of an REPL with the standard library loaded.
pub fn init<EC: EvalCache>(trace: impl Write + 'static) -> Result<ReplImpl<EC>, Error> {
    let mut repl = ReplImpl::new(trace);
    repl.load_stdlib()?;
    Ok(repl)
}

/// Evaluate an input.
pub fn input<R: Repl>(repl: &mut R, line: &str) -> Result<InputResult, InputError> {
    if line.trim().is_empty() {
        Ok(InputResult::Blank)
    } else if line.starts_with(':') {
        let cmd = line.chars().skip(1).collect::<String>().parse::<Command>();
        match cmd {
            Ok(Command::Load(_)) => Err(InputError::Other(String::from(
                ":load is not enabled on this REPL.",
            ))),
            Ok(Command::Typecheck(exp)) => repl
                .typecheck(&exp)
                .map(|typ| InputResult::Success(format!("Ok: {typ}")))
                .map_err(InputError::from),
            Ok(Command::Query(path)) => repl
                .query(path)
                .map(|t| {
                    let mut buffer = Cursor::new(Vec::<u8>::new());
                    query_print::write_query_result(
            
    
pub fn input<R: Repl>(repl: &mut R, line: &str) -> Result<InputResult, InputError> {
    if line.trim().is_empty() {
        Ok(InputResult::Blank)
    } else if line.starts_with(':') {
        let cmd = line.chars().skip(1).collect::<String>().parse::<Command>();
        match cmd {
            Ok(Command::Load(_)) => Err(InputError::Other(String::from(
                ":load is not enabled on this REPL.",
            ))),
            Ok(Command::Typecheck(exp)) => repl
                .typecheck(&exp)
                .map(|typ| InputResult::Success(format!("Ok: {typ}")))
                .map_err(InputError::from),
            Ok(Command::Query(path)) => repl
                .query(path)
                .map(|t| {
                    let mut buffer = Cursor::new(Vec::<u8>::new());
                    query_print::write_query_result(
                        &mut buffer,
                        &t,
                        query_print::Attributes::default(),
                    )
                    .unwrap();
                    InputResult::Success(String::from_utf8(buffer.into_inner()).unwrap())
                })
                .map_err(InputError::from),
            Ok(Command::Print(exp)) => repl
                .eval_full(&exp)
                .map(|res| match res {
                    EvalResult::Evaluated(rt) => InputResult::Success(format!("{rt}\n")),
                    EvalResult::Bound(_) => InputResult::Blank,
                })
                .map_err(InputError::from),
            Ok(Command::Help(arg)) => {
                let mut buffer = Cursor::new(Vec::<u8>::new());
                print_help(&mut buffer, arg.as_deref()).unwrap();
                Ok(InputResult::Success(
                    String::from_utf8(buffer.into_inner()).unwrap(),
                ))
            }
            Ok(Command::Exit) => Ok(InputResult::Success(String::from("Exiting"))),
            Err(err) => Err(InputError::from(Error::from(err))),
        }
    } else {
        repl.eval_full(line)
            .map(|eval_res| match eval_res {
                EvalResult::Evaluated(rt) => InputResult::Success(format!("{rt}\n")),
                EvalResult::Bound(_) => InputResult::Success(String::new()),
            })
            .map_err(InputError::from)
    }
}