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_tuse penftype(string)::astringreal(R8P)::real_logical::test_passed(1)astring='3.4e9'real_=astring%to_number(kind=1._R8P)test_passed(1)=real_==3.4e9_R8Pprint'(L1)',all(test_passed)endprogram volatile_doctest