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: lib.rs
    path of file: ./repos/Theseus/old_crates/less/src
    
    the code of the file until where you have to start completion: //! A text file reader which allows the user using `Up` and `Down` to scroll the screen.

#![no_std]

#[macro_use] extern crate alloc;
extern crate task;
extern crate getopts;
extern crate path;
extern crate fs_node;
extern crate keycodes_ascii;
extern crate libterm;
extern crate spin;
extern crate app_io;
extern crate stdio;
extern crate core2;
#[macro_use] extern crate log;

use keycodes_ascii::{Keycode, KeyAction};
use core::str;
use alloc::{
    vec::Vec,
    string::{String, ToString},
    sync::Arc,
};
use getopts::Options;
use path::Path;
use fs_node::FileOrDir;
use alloc::collections::BTreeMap;
use libterm::Terminal;
use spin::Mutex;
use stdio::{StdioWriter, KeyEventQueueReader};
use core2::io::Write;

/// The metadata for each line in the file.
struct LineSlice {
    /// The starting index in the String for a line. (inclusive)
    start: usize,
    /// The ending index in the String for a line. (exclusive)
    end: usize
}

/// Read the whole file to a String.
fn get_content_string(file_path: String) -> Result<String, String> {
    let Ok(curr_wd) = task::with_current_task(|t| t.get_env().lo
    
fn get_content_string(file_path: String) -> Result<String, String> {
    let Ok(curr_wd) = task::with_current_task(|t| t.get_env().lock().working_dir.clone()) else {
        return Err("failed to get current task".to_string());
    };
    let path = Path::new(file_path);
    
    // navigate to the filepath specified by first argument
    match path.get(&curr_wd) {
        Some(file_dir_enum) => { 
            match file_dir_enum {
                FileOrDir::Dir(directory) => {
                    Err(format!("{:?} is a directory, cannot 'less' non-files.", directory.lock().get_name()))
                }
                FileOrDir::File(file) => {
                    let mut file_locked = file.lock();
                    let file_size = file_locked.len();
                    let mut string_slice_as_bytes = vec![0; file_size];
                    
                    let _num_bytes_read = match file_locked.read_at(&mut string_slice_as_bytes, 0) {
                        Ok(num) => num,
                        Err(e) => {
                            return Err(format!("Failed to read {:?}, error {:?}",
                                               file_locked.get_name(), e))
                        }
                    };
                    let read_string = match str::from_utf8(&string_slice_as_bytes) {
                        Ok(string_slice) => string_slice,
                        Err(utf8_err) => {
                            return Err(format!("File {:?} was not a printable UTF-8 text file: {}",
                                               file_locked.get_name(), utf8_err))
                        }
                    };
                    Ok(read_string.to_string())
                }
            }
        },
        _ => {
            Err(format!("Couldn't find file at path {}", path))
        }
    }
}