Or you can read it from the published cloud notebook version: https://www.wolframcloud.com/env/silviah/Published/How%20to%20make%20a%20Christmas%20card%20on%20the%20cloud.nb
(How the tree is modeled is not covered in this note though. Just some cloud API 101.)
@MichaelE2 They were talking about something like this in one of the live-streams if I remember correctly. I think the were planning to extend support of Transpose to arbitrary heads, including Association via the AllowedHeads (currently undocumented for Transpose) option, but it doesn't seem to work yet
