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: response.rs
    path of file: ./repos/iroh/iroh-net/src/portmapper/pcp/protocol
    
    the code of the file until where you have to start completion: //! A PCP response encoding and decoding.

use derive_more::Display;
use num_enum::{IntoPrimitive, TryFromPrimi
    
    fn encode(&self) -> Vec<u8> {
        let Response {
            lifetime_seconds,
            epoch_time,
            data,
        } = self;
        let mut buf = Vec::with_capacity(Self::MIN_SIZE);
        // version
        buf.push(Version::Pcp.into());
        // response indicator and opcode
        let opcode: u8 = data.opcode().into();
        buf.push(Response::RESPONSE_INDICATOR | opcode);
        // reserved
        buf.push(0);
        // result code
        buf.push(ResultCode::Success.into());
        // lifetime
        for b in lifetime_seconds.to_be_bytes() {
            buf.push(b);
        }
        // epoch
        for b in epoch_time.to_be_bytes() {
            buf.push(b);
        }
        // reserved
        for _ in 12..Response::MIN_SIZE {
            buf.push(0)
        }
        data.encode_into(&mut buf);
        buf
    }