Function median 

pub fn median(numbers: &Vec<i32>) -> Median

Calculates the median of the elements in the given vector.

Example

For a vector with an odd number of elements, the value of the middle element will be returned:

let numbers = vec![1, 2, 3, 4, 5];
match mememo::median(&numbers) {
    mememo::MiddleSingle(got) => assert_eq!(3, got),
    _ => panic!("wrong median calculation"),
}

For a vector with an even number of elements, the mean of the two middle elements will be calculated:

let numbers = vec![1, 2, 3, 4];
match mememo::median(&numbers) {
    mememo::MiddleTwoMean(got) => assert_eq!(2.5, got),
    _ => panic!("wrong median calculation"),
};