// ... I have a BufferedReader giving me file and a HashMap giving me map
for line in file.lines() {
    let s = line.unwrap();
    // Sample: "appadmin....................................." dots are whitespace and should get trimmed off the keys
    if s.starts_with("<FLTR>") {
        let user = s.slice(97, 142).trim();
        if map.contains_key(&user) {
            println!("found!");
        }
    }
}

// Gives the following:
D:\Rust\ARLogFilter\src\testing.rs:17:21: 17:22 error: `s` does not live long enough
D:\Rust\ARLogFilter\src\testing.rs:17           let user = s.slice(97, 142).trim();
                                                           ^
D:\Rust\ARLogFilter\src\testing.rs:5:11: 23:2 note: reference must be valid for the block at 5:10...
D:\Rust\ARLogFilter\src\testing.rs:5 fn main() {
D:\Rust\ARLogFilter\src\testing.rs:6     let mut map = HashMap::new();
D:\Rust\ARLogFilter\src\testing.rs:7     map.insert("appadmin", "foo");
D:\Rust\ARLogFilter\src\testing.rs:8     map.insert("Remedy Application Service", "bar");
D:\Rust\ARLogFilter\src\testing.rs:9
D:\Rust\ARLogFilter\src\testing.rs:10     // input file
                                      ...
D:\Rust\ARLogFilter\src\testing.rs:13:27: 22:3 note: ...but borrowed value is only valid for the block at 13:26
D:\Rust\ARLogFilter\src\testing.rs:13   for line in file.lines() {
D:\Rust\ARLogFilter\src\testing.rs:14       let s = line.unwrap();
D:\Rust\ARLogFilter\src\testing.rs:15       // Sample: "appadmin....................................." dots are whitespace and should get trimmed off the keys
D:\Rust\ARLogFilter\src\testing.rs:16       if s.starts_with("<FLTR>") {
D:\Rust\ARLogFilter\src\testing.rs:17           let user = s.slice(97, 142).trim();
D:\Rust\ARLogFilter\src\testing.rs:18           if map.contains_key(&user) {
                                      ...
error: aborting due to previous error