DynamoVisualProgramming.DynamoServices by Autodesk

<PackageReference Include="DynamoVisualProgramming.DynamoServices" Version="2.1.0-beta6634" />

 ArbitraryDimensionArrayImportAttribute

This attribute is used to marshal parameters or return value of a method as arbitrary dimension array in DesignScript VM. Usually this attribute is expected to be applied on IEnumerable derived object types. This attribute should be used if you expect the IEnumerable parameters or return value may hold nested collection.
using System; namespace Autodesk.DesignScript.Runtime { [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.ReturnValue)] public sealed class ArbitraryDimensionArrayImportAttribute : Attribute { } }