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use std::io::BufRead;

pub fn find_matches<R: BufRead>(content: R, pattern: &str, mut writer: impl std::io::Write) {
    for line in content.lines() {
        match line {
            Ok(text) => {
                if text.contains(pattern) {
                    writeln!(writer, "{}", text).expect("couldn't write");
                }
            }
            Err(error) => { panic!(error) }
        }
    }
}

#[test]
fn find_a_match() {
    let mut result = Vec::new();
    find_matches("lorem ipsum\ndolor sit amet".as_bytes(), "lorem", &mut result);
    assert_eq!(result, b"lorem ipsum\n");
}