Flow belongs to chain

chain/flow.go

@@ -0,0 +1,39 @@
+package chain
+
+type (
+	Flow int
+)
+
+const (
+	UnknownFlow Flow = iota
+	SequentialFlow
+	ParallelFlow
+	DelayedFlow
+)
+
+var (
+	flowSymbols = map[string]Flow{
+		"s": SequentialFlow,
+		"p": ParallelFlow,
+		"d": DelayedFlow,
+	}
+	flowNames = map[Flow]string{
+		UnknownFlow:    "Unknown",
+		SequentialFlow: "Sequential",
+		ParallelFlow:   "Parallel",
+		DelayedFlow:    "Delayed",
+	}
+)
+
+func FlowOf(f string) Flow {
+	if flow, ok := flowSymbols[f]; ok {
+		return flow
+	} else {
+		return UnknownFlow
+	}
+}
+
+func (f Flow) String() string {
+	name, _ := flowNames[f]
+	return name
+}