Function flatten 

pub fn flatten<T, I, O>(input: Array<Array<T, I>, O>) -> Array<T, Prod<I, O>>
where
    I: Mul<O> + ArraySize,
    I::Output: ArraySize,
    O: ArraySize,
    T: Default + Copy,

Flatten an array of arrays into a single contigues array.

Examples

use array_fusion::hybrid_array::Array;
use array_fusion::hybrid_array::sizes::{U2, U3, U6};
use array_fusion::chunks::flatten;

let array_of_arrays: Array<Array<u8, U2>, U3> = Array([
    Array([1, 2]),
    Array([3, 4]),
    Array([5, 6]),
]);

let flattened: Array<u8, U6> = flatten(array_of_arrays);

assert_eq!(flattened, Array([1, 2, 3, 4, 5, 6]));