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: filter.rs
    path of file: ./repos/metrics/metrics-util/src/layers
    
    the code of the file until where you have to start completion: use crate::layers::Layer;
use aho_corasick::{AhoCorasick, AhoCorasickBuilder, AhoCorasickKind};
use metrics::{Counter, Gauge, Histogram, Key, KeyName, Metadata, Recorder, SharedString, Unit};

/// Filters and dis
    
    fn layer(&self, inner: R) -> Self::Output {
        let mut automaton_builder = AhoCorasickBuilder::new();
        let automaton = automaton_builder
            .ascii_case_insensitive(self.case_insensitive)
            .kind(self.use_dfa.then_some(AhoCorasickKind::DFA))
            .build(&self.patterns)
            // Documentation for `AhoCorasickBuilder::build` states that the error here will be
            // related to exceeding some internal limits, but that those limits should generally be
            // large enough for most use cases.. so I'm making the executive decision to consider
            // that "good enough" and treat this as an exceptional error if it does occur.
            .expect("should not fail to build filter automaton");
        Filter { inner, automaton }
    }