Macro dbgbb_flatten 

macro_rules! dbgbb_flatten {
    ($x:expr, depth => 1) => { ... };
    ($x:expr, depth => 2) => { ... };
    ($x:expr, depth => 3) => { ... };
    ($x:expr, depth => 4) => { ... };
}

Send each element to the server.

Usage:

use dbgbb::dbgbb_flatten;
let a = vec![vec![1u32, 2], vec![3, 4]];
dbgbb_flatten!(a, depth => 1);
dbgbb_flatten!(a, depth => 2);