Function decline 

pub fn decline(n: i64, one: &str, two: &str, five: &str) -> String

Returns the correct Russian noun declension form based on a number.

Examples

use chislo::decline;

assert_eq!(decline(1, "рубль", "рубля", "рублей"), "рубль");
assert_eq!(decline(5, "рубль", "рубля", "рублей"), "рублей");