def demo_shellFeatures_add(rootComp: adsk.fusion.Component):
face = _ui.selectEntity('Select a face to open as part of a shell feature.', 'Faces').entity
bodiesAndFaces = adsk.core.ObjectCollection.create()
bodiesAndFaces.add(face)
shellFeatures = rootComp.features.shellFeatures
input: adsk.fusion.ShellFeatureInput = shellFeatures.createInput(bodiesAndFaces, True)
input.insideThickness = adsk.core.ValueInput.createByReal(0.25)
shellFeature = shellFeatures.add(input)