Clean up callback interfaces.

service/datastore/toggle_string.go

+// Code generated by "stringer -type=Toggle"; DO NOT EDIT
+
+package datastore
+
+import "fmt"
+
+const _Toggle_name = "AutoOnOff"
+
+var _Toggle_index = [...]uint8{0, 4, 6, 9}
+
+func (i Toggle) String() string {
+        if i >= Toggle(len(_Toggle_index)-1) {
+                return fmt.Sprintf("Toggle(%d)", i)
+        }
+        return _Toggle_name[_Toggle_index[i]:_Toggle_index[i+1]]
+}