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 vecfor_R16Ptype(vector_R16P)::ptpt=ex_R16P+ey_R16Pcall pt%printf(prefix='[x, y, z] = ',sep=', ')endprogram volatile_doctest