cpython/Include/pyexpat.h

/* Stuff to export relevant 'expat' entry points from pyexpat to other
 * parser modules, such as cElementTree. */

/* note: you must import expat.h before importing this module! */

#define PyExpat_CAPI_MAGIC …
#define PyExpat_CAPSULE_NAME …

struct PyExpat_CAPI
{ … };