* `[[n,writeln],[Variable1]]` e.g. `[[n,writeln],[[v,a]]]` writes `[v,a]` which is `"hello"`

* `[[n,atom_string],[Variable1,Variable2]]` e.g. `[[n,atom_string],[a,[v,b]]]` returns `[v,b]="a"` or `[[n,atom_string],[[v,b],"a"]]` returns `[v,b]=a`

* (1) `[[n,call],[Function,Arguments]]` e.g. `[[n,call],[[n,member2a],[[v,b],["a","b","c"]]]]` returns `[v,b]=a`

* (2) `[[n,call],[[lang,Lang],Debug,[Function,Arguments],Functions]]` e.g. `[[n,call],[[lang,same],same,[[n,member2a],[[v,b],["a","b","c"]]],
[[[n,member2a],[[v,b],[v,a]],":-",
	[[[n,member],[[v,b],[v,a]]]]]]]]` returns `[v,b]="a"`, where Lang may be e.g. `"en"`, etc., or `same` (meaning the same language as the parent predicate) and Debug may be `on`, `off` or `same` (meaning the same debug status as the parent predicate).