Escape regular expression special characters in order to make it able to be concatenated safely by users.
```rust extern crate escape_regex;
extern crate regex;
use regex::Regex;
let pattern = "123*456"; let escapedpattern = escaperegex::escape_string(pattern);
let reg = Regex::new(&escaped_pattern).unwrap();
asserteq!(true, reg.ismatch("0123*4567")); ```
https://crates.io/crates/escape-regex
https://docs.rs/escape-regex