.. warning::

    The code provided above / on this page uses an external
    native (non-Python) library through a ``cimport`` (``cython.cimports``).
    Cython compilation enables this, but there is no support for this from
    plain Python. Trying to run this code from Python (without compilation)
    will fail when accessing the external library.
    This is described in more detail in :ref:`calling-c-functions`.