save_core_families
==================

.. py:function:: t3toolbox.backend.common.save_core_families(file, families)

   .. code-block:: python

      def save_core_families(
              file,      # path or open file object to write the .npz to
              families,  # sequence of core-families, each a sequence of arrays
      ) -> None:


   Save a sequence of core-families (each a sequence of arrays) to a ``.npz`` file.

   Uses ``'f{family_index}_{core_index}'`` keys so :py:func:`load_core_families` can regroup them.
   Shared by the frontend ``save`` methods (T3Frame, T3Variations, T3Tangent).