let rec breadthFirstList (DP(n,i,ds))  =
    n + " -> " + "(" + String.join " " (getSubdepartmentNames(ds)) + ")"
and getSubdepartmentNames ds =
    match ds with
    | [] -> ""
    | DP(ns,is,dss) as dep :: rest -> breadthFirstList dep + ", " + getSubdepartmentNames(rest);;