tt_zipper_left_to_right
=======================

.. py:function:: t3toolbox.backend.tt_operations.tt_zipper_left_to_right(coresA, coresB)

   .. code-block:: python

      def tt_zipper_left_to_right(
              coresA:     typ.Sequence[NDArray],  # len=d, elm_shape=stack_shape+(rAi, ni, rA(i+1))
              coresB:     typ.Sequence[NDArray],  # len=d, elm_shape=stack_shape+(rBi, ni, rB(i+1))
      ) -> typ.Tuple[NDArray, ...]:  # zipper matrices, len=d+1, elm_shape=stack_shape+(rAi, rBi)


   Accumulate left-to-right the partial contractions of two TT chains sharing tensor indices.

   Returns d+1 matrices Z_i; Z_0 is the (left-boundary) ones matrix and Z_(i+1) contracts Z_i with
   cores A_i, B_i. Stack-aware. **Polymorphic over the representation** (the scan reuse rule): a ragged
   core tuple gives a ragged ``xscan`` and a tuple of d+1 matrices; a uniform TT *supercore*
   (``(d,)+stack+(rA, n, rB)``, detected as a bare ndarray) gives the uniform ``xscan`` over the leading
   mode axis -- still returned as a tuple of d+1 matrices (the caller stacks if it wants a supercore).