:- multifile term_expansion/2.
The user may override the standard transformations to be done by
expand_term/2 by defining clauses for
term_expansion/2 first; if it succeeds, the
standard grammar rule expansion is not tried.
expand_term/2 always calls
term_expansion/2 in module
Therefore, to be visible to
either be defined in or imported into module
Alternatively, you may define it in any module by using module
prefixing; refer to ref-mod-vis.
This hook predicate may now return a list of terms rather than a single term. Each of the terms in the list is then treated as a separate clause.