v2.0.0 (Rangifer tarandus platyrhynchus)

@jupyrdf/jupyter-elk 2.0.0

• added control layer for displaying jupyter widgets based on currently selected nodes.

Rearchitecting core logic around:

• Element data model paralleling elkjson using Pydantic for serialization and validation.
• modular Pipes that can transform the elkjson. For example, performing text label sizing before doing a full diagram render.