Nodes of different colours represent the following:
Solid arrows point from a procedure to one which it calls. Dashed
arrows point from an interface to procedures which implement that interface.
This could include the module procedures in a generic interface or the
implementation in a submodule of an interface in a parent module.
public pure module subroutine do_concurrent_output_distribution(nintervals, speed, freq, emp_distribution, k, output_distribution) bind(C)