Atom_split/3 is not defined?

[EricGT]

See: pakage list_util (docs)

Also see: Package install errors - How to resolve after SWI-Prolog changed to using HTTPS

example:

?- list_util:split_at(2,[a,b,c,d,e],Prefix,Suffix).
Prefix = [a, b],
Suffix = [c, d, e].