
  -spec delete_module(Module) -> true | undefined when Module :: module().

  Makes the current code for Module become old code and deletes
  all references for this module from the export table. Returns 
  undefined if the module does not exist, otherwise true.

  Warning:
    This BIF is intended for the code server (see code(3)) and
    is not to be used elsewhere.

  Failure: badarg if there already is an old version of Module.
