Nodes of different colours represent the following:
Solid arrows point from a file to a file which it depends on. A file
is dependent upon another if the latter must be compiled before the former
can be.
program volatile_doctestuse stringifor_string_ttype(string)::astringlogical::test_passed(2)test_passed(1)=astring%is_allocated().eqv..false.astring='hello'test_passed(2)=astring%is_allocated().eqv..true.print'(L1)',all(test_passed)endprogram volatile_doctest