Function to_roman 

pub fn to_roman(number: i64) -> Result<String>

A number from 1 to 3999 as a Roman numeral: music21’s toRoman.

use music21::common::numbertools::to_roman;

assert_eq!(to_roman(1999)?, "MCMXCIX");
assert!(to_roman(0).is_err());

Errors

A number outside that range.