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: util.rs
    path of file: ./repos/ffsend/src
    
    the code of the file until where you have to start completion: #[cfg(feature = "clipboard-crate")]
extern crate clip;
#[cfg(feature = "clipboard-bin")]
extern crate which;

use std
    
fn derive_bool(input: &str) -> Option<bool> {
    // Process the input
    let input = input.trim().to_lowercase();

    // Handle short or incomplete answers
    match input.as_str() {
        "y" | "ye" | "t" | "1" => return Some(true),
        "n" | "f" | "0" => return Some(false),
        _ => {}
    }

    // Handle complete answers with any suffix
    if input.starts_with("yes") || input.starts_with("true") {
        return Some(true);
    }
    if input.starts_with("no") || input.starts_with("false") {
        return Some(false);
    }

    // The answer could not be determined, return none
    None
}