How do i set the ZOSAPI.Editors.LDE.ISurfaceTilted.Y_Tangent property in Python

Hi,
i have problems to find the right syntax to set the Y-Tangent property of a tilted surface in ZOSAPI for Python. The following code works exept for the last part.

TheLDE = TheSystem.LDE
surf0 = TheLDE.GetSurfaceAt(0)
surf0.ChangeType(surf0.GetSurfaceTypeSettings(ZOSAPI.Editors.LDE.SurfaceType.Tilted))
surf0.Thickness = 2
surf0.ISurfaceTilted.Y_Tangent = 3

Thanks in advance!