On one hand, there is my research draft of what one could do to accommodate nested dictionaries (structure with tree-like interfaces) inside machine learning frameworks optimized for hangling "tensors" (flat multidimensional arrays).

https://github.com/anhinga/2021-notes/tree/main/research-drafts

"Dataflow matrix machines, tree-shaped flexible tensors, neural architecture search, and PyTorch" (Jan 2021)