diff --git a/sdks/go/pkg/beam/core/runtime/exec/input.go b/sdks/go/pkg/beam/core/runtime/exec/input.go
index dff79fe..a3ccb78 100644
--- a/sdks/go/pkg/beam/core/runtime/exec/input.go
+++ b/sdks/go/pkg/beam/core/runtime/exec/input.go
@@ -60,6 +60,12 @@
 	inputs[t] = maker
 }
 
+// IsInputRegistered returns whether an input maker has already been registered.
+func IsInputRegistered(t reflect.Type) bool {
+	_, exists := inputs[t]
+	return exists
+}
+
 type reIterValue struct {
 	t  reflect.Type
 	s  ReStream