+-- Helper functions
+
+local function group_merge(group1, group2)
+ for name, values in pairs(group2) do
+ if group1[name] == nil then
+ group1[name] = values
+ else
+ for _, v in pairs(values) do
+ table.insert(group1[name], v)
+ end
+ end
+ end
+
+ return group1
+end
+