const Key = stampit.props({
auth.key === 'my secret key'
auth.key === 'ha ha ha' // oops :(
const FrozenKey = stampit.propertyDescriptors(Key, { // composing the two
key: { // this is a standard JavaScript property descriptor
auth.key === 'my secret key'
auth.key === 'my secret key' // OK!!! The "key" was not overwritten.