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)::astringastring='y'print"(L1)",astring%repeat('x',5)//''=='xxxxx'endprogram volatile_doctest