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)::astringinteger(I4P)::integer_logical::test_passed(1)astring='127'integer_=astring%to_number(kind=1_I4P)test_passed(1)=integer_==127_I4Pprint'(L1)',all(test_passed)endprogram volatile_doctest