+GSList *list_pds = NULL;
+
+/*
+ * Here's a quick overview of Python/C API reference counting.
+ *
+ * Check the Python/C API docs for what type of reference a function returns.
+ *
+ * - If it returns a "new reference", you're responsible to Py_XDECREF() it.
+ *
+ * - If it returns a "borrowed reference", you MUST NOT Py_XDECREF() it.
+ *
+ * - If a function "steals" a reference, you no longer are responsible for
+ * Py_XDECREF()ing it (someone else will do it for you at some point).
+ */