#pred Spec :: Template. directive.
| Spec | - is a term Head::Template, where Head is an sCASP atom where the variables are represented as $(Name) and Template is a string that embeds "@(Var)", "@(Var:Type)", "{{Var}}" or "{{Var:Type}}" |
| Pred | - is a term `Head::format(Fmt, Args)`, where Fmt contains
~p and the arguments are of the shape @($(Var):Type), which is
printed as "<Var>, a <Type>" |