INSTANCE adder#1; extracted_from = {equation#1}; covers = equation#1; addends = ?addends; sum = expression#1; END_INSTANCE;
INSTANCE adder#2; extracted_from = {equation#2}; covers = equation#2; addends = {expression#2, ?y}; sum = ?z; END_INSTANCE;
INSTANCE adder#3; addends = ?addends; sum = ?sum; END_INSTANCE;