user, normally not defined. Query
and
Bindings represents the query read from the user and the
names of the free variables as obtained using read_term/3.
If this predicate succeeds, it should bind Expanded and ExpandedBindings
to the query and bindings to be executed by the top level. This
predicate is used by the top level (prolog/0).
See also expand_answer/2
and
term_expansion/2.