Function fips_codes::state_and_county_by_fips_id

pub fn state_and_county_by_fips_id(
    id: &str
) -> Option<(&'static str, &'static str)>

Does not distinguish between “invalid” strings and simply incorrect ones; either way, you will only get None back.

use fips_codes::state_and_county_by_fips_id;
assert_eq!(state_and_county_by_fips_id("53033"), Some(("Washington", "King County")));
assert_eq!(state_and_county_by_fips_id("53010"), None);
assert_eq!(state_and_county_by_fips_id("530100"), None);
assert_eq!(state_and_county_by_fips_id("53-10"), None);