If the random move iterator first randomly selects an employee and then randomly selects an index to move a given task to, then positions in larger task list variables have smaller chance of being selected than positions in smaller task lists:

All possible target positions for a given moved task should have the same probability of being selected by the random move iterator.

NOTE: navigable map is a nice-to-have optimization. The first implementation will use a for loop to identify the target employee based on a single random number. Leave a TODO note to try and benchmark the navigable map approach (also try with extremely large data sets that we don't have yet).