Read environment variables by lower, upper case or case-insensitive keys.
Unicode support for keys is enabled through the unicode feature.
use unkasedenv::{uncased_var, lower_var, upper_var};
env::set_var("HeLlO", "world");
assert_eq!(uncased_var("Hello"), Ok("world".to_string()));
assert_eq!(lower_var("hello"), Ok("world".to_string()));
assert_eq!(upper_var("HELLO"), Ok("world".to_string()));
/* with `unicode` feature enabled */
env::set_var("Maße", "42");
assert_eq!(uncased_var("mAßE"), Ok("42".to_string()));
assert_eq!(lower_var("maße"), Ok("42".to_string()));
assert_eq!(upper_var("MASSE"), Ok("42".to_string()));