ex basic::subs(const ex & e, unsigned options) const
{
if (e.info(info_flags::relation_equal)) {
- return subs(lst(e), options);
+ return subs(lst(e.lhs()), lst(e.rhs()), options);
}
if (!e.info(info_flags::list)) {
throw(std::invalid_argument("basic::subs(ex): argument must be a list"));