add chain hop

chain/hop.go

@@ -0,0 +1,20 @@
+package chain
+
+import "context"
+
+type SelectOptions struct {
+	Addr string
+}
+
+type SelectOption func(*SelectOptions)
+
+func AddrSelectOption(addr string) SelectOption {
+	return func(o *SelectOptions) {
+		o.Addr = addr
+	}
+}
+
+type Hop interface {
+	Nodes() []*Node
+	Select(ctx context.Context, opts ...SelectOption) *Node
+}