This node set the shading of the input object to smooth or flat.
Inputs
Object - An Object.
Smooth - A boolean which if True will shade the object smooth
and if False will shade the object flat.
Outputs
Object - The input object.
Note
If you shaded an object smooth and it get rendered black, then its
normals are null vectors and you will have to recalculate the normals
using the Recalculate Normals Node.