This subtype of PyObject represents an opaque value, useful
for C extension modules who need to pass an opaque value (as a
void* pointer) through Python code to other C code. It is
often used to make a C function pointer defined in one module
available to other modules, so the regular import mechanism can be
used to access C APIs defined in dynamically loaded modules.
Return true if its argument is a PyCObject.
void (*destr)(void *))
Return value:New reference.
Create a PyCObject from the void *cobj. The
destr function will be called when the object is reclaimed,
unless it is NULL.