This class represents a NPZ file, the preferable format for Biotite internal structure storage.
This subpackage is used for reading and writing an
AtomArrayStack using the internal NPZ file format. This binary
format is used to store NumPy arrays. Since atom arrays and stacks are
completely built on NumPy arrays, this format is preferable for
Biotite internal usage due to fast I/O operations and preservation
of all atom annotation arrays.