Function find 

pub fn find(
    root: &Path,
    symbol: &str,
    limit: usize,
    opts: &FindOptions,
) -> Result<FindResult>

cyberbrain find <symbol> (SPEC §10).

Errors are user errors (exit code 1): an empty symbol, a zero limit, a root that is not a directory, an ignore file that does not parse. Nothing else fails the call — an unreadable file is a count, not an error.