Function unique_name_from_namespace 

pub fn unique_name_from_namespace(namespaced: &str) -> Option<&'static str>

The unique name a namespaced name stands for, localeOfComposition for humdrum:OPC: music21’s namespaceNameToUniqueName. A name outside the vocabulary stands for none.

use music21::metadata::unique_name_from_namespace;

assert_eq!(unique_name_from_namespace("humdrum:OPC"), Some("localeOfComposition"));
assert_eq!(unique_name_from_namespace("soundtracker:SampleName"), None);