an class="boring">use std::env;
</span><span class="boring">
</span><span class="boring">struct Config {
</span><span class="boring">    query: String,
</span><span class="boring">    filename: String,
</span><span class="boring">    case_sensitive: bool,
</span><span class="boring">}
</span><span class="boring">
</span>impl Config {
    pub fn new(mut args: std::env::Args) -&gt; Result&lt;Config, &amp;'static str&gt; {
        args.next();

        let query = match args.next() {
            Some(arg) =&gt