--- /dev/null
+package proposal
+
+import "github.com/vapor/protocol"
+
+type byTime []*protocol.TxDesc
+
+func (a byTime) Len() int { return len(a) }
+func (a byTime) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
+func (a byTime) Less(i, j int) bool { return a[i].Added.Before(a[j].Added) }