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: openpgpkey.rs
    path of file: ./repos/hickory-dns/crates/proto/src/serialize/txt/rdata_parsers
    
    the code of the file until where you have to start completion: // Copyright 2019 Benjamin Fry <benjaminfry@me.com>
//
// Licensed under the Apache License, Vers
    
pub(crate) fn parse<'i, I: Iterator<Item = &'i str>>(mut tokens: I) -> ParseResult<OPENPGPKEY> {
    let encoded_public_key = tokens.next().ok_or(ParseErrorKind::Message(
        "OPENPGPKEY public key field is missing",
    ))?;
    let public_key = data_encoding::BASE64.decode(encoded_public_key.as_bytes())?;
    Some(OPENPGPKEY::new(public_key))
        .filter(|_| tokens.next().is_none())
        .ok_or_else(|| ParseErrorKind::Message("too many fields for OPENPGPKEY").into())
}