ut3_squash_tails
================

.. py:function:: t3toolbox.backend.ut3_operations.ut3_squash_tails(data)

   .. code-block:: python

      def ut3_squash_tails(data: UT3Data) -> UT3Data:


   Sum the leading/trailing TT bonds down to rank 1 (preserves the tensor), updating those edge
   masks to rank 1. Operates on the full .data tuple.