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 penf_stringifyuse penfcharacter(len=:,kind=ASCII),allocatable::stringstring=str_ascii('I was DEFAULT kind, but now I am ASCII')print"(A)",stringendprogram volatile_doctest