isGroupEqual function
Implementation
isGroupEqual(List<GroupData> serverGroup, List<GroupData> cartGroup){
for (var pair in zip([serverGroup, cartGroup])){
var s = pair[0]; // serverGroup
var c = pair[1]; // cartGroup
if (s.id == c.id)
isPricesEqual(s.price, c.price);
else
_notEqual = true;
}
}