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: link.rs
    path of file: ./repos/holochain/crates/holochain_types/src
    
    the code of the file until where you have to start completion: //! Links interrelate entries in a source chain.

use holo_hash::ActionHash;
use holo_hash::AgentPubKey;
use holo_hash::AnyLinkableHash;
use holochain_serialized_bytes::prelude::*;
use holochain_zome_types::prelude::*;
use regex::Regex;

use crate::dht_op::DhtOpError;
use crate::dht_op::DhtOpResult;
use crate::dht_op::DhtOpType;
use crate::dht_op::RenderedOp;
use crate::
    
    pub fn to_regex_string(self) -> Result<String, String> {
        let re_string: String = match self {
            LinkMatch::Any => ".*".into(),
            LinkMatch::Exactly(s) => "^".to_owned() + &regex::escape(&s.into()) + "$",
            LinkMatch::Regex(s) => s.into(),
        };
        // check that it is a valid regex
        match Regex::new(&re_string) {
            Ok(_) => Ok(re_string),
            Err(_) => Err("Invalid regex passed to get_links".into()),
        }
    }