text: #ifndef Py_CPYTHON_PYSTATE_H
  #  error "this header file must not be included directly"
  #endif
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #include "cpython/initconfig.h"
  
  PyAPI_FUNC(int) _PyInterpreterState_RequiresIDRef(PyInterpreterState *);
  PyAPI_FUNC(void) _PyInterpreterState_RequireIDRef(PyInterpreterState *, int);
  
  PyAPI_FUNC(PyObject *) _PyInterpreterState_GetMainModule(PyInterpreterState *);
  
  /* State unique per thread */
  
  /* Py_tracefunc return -1 when raising an exception, or 0 for success. */
  typedef int (*Py_tracefunc)(PyObject *, struct _frame *, int, PyObject *);
  
  /* The following values are used for 'what' for tracefunc functions
   *
   * To add a new kind of trace event, also update "trace_init" in
   * Python/sysmodule.c to define the Python level event name
   */
  #define PyTrace_CALL 0
  #define PyTrace_EXCEPTION 1
  #define PyTrace_LINE 2
  #define PyTrace_RETURN 3
  #define PyTrace_C_CALL 4
  #define PyTrace_C_EXCEPTION 5
  #define PyTrace_C_RETURN 6
  #define PyTrace_OPCODE 7
  
  
  typedef struct _err_stackitem {
      /* This struct represents an entry on the exception stack, which is a
       * per-coroutine state. (Coroutine in the computer science sense,
       * including the thread and generators).
       * This ensures that the exception state is not impacted by "yields"
       * from an except handler.
       */
      PyObject *exc_type, *exc_value, *exc_traceback;
  
      struct _err_stackitem *previous_item;
  
  } _PyErr_StackItem;
  
  
  // The PyThreadState typedef is in Include/pystate.h.
  struct _ts {
      /* See Python/ceval.c for comments explaining most fields */
  
      struct _ts *prev;
      struct _ts *next;
      PyInterpreterState *interp;
  
      struct _frame *frame;
      int recursion_depth;
      char overflowed; /* The stack has overflowed. Allow 50 more calls
                          to handle the runtime error. */
      char recursion_critical; /* The current calls must not cause
                                  a stack overflow. */
      int stackcheck_counter;
  
      /* 'tracing' keeps track of the execution depth when tracing/profiling.
         This is to prevent the actual trace/profile code from being recorded in
         the trace/profile. */
      int tracing;
      int use_tracing;
  
      Py_tracefunc c_profilefunc;
      Py_tracefunc c_tracefunc;
      PyObject *c_profileobj;
      PyObject *c_traceobj;
  
      /* The exception currently being raised */
      PyObject *curexc_type;
      PyObject *curexc_value;
      PyObject *curexc_traceback;
  
      /* The exception currently being handled, if no coroutines/generators
       * are present. Always last element on the stack referred to be exc_info.
       */
      _PyErr_StackItem exc_state;
  
      /* Pointer to the top of the stack of the exceptions currently
       * being handled */
      _PyErr_StackItem *exc_info;
  
      PyObject *dict;  /* Stores per-thread state */
  
      int gilstate_counter;
  
      PyObject *async_exc; /* Asynchronous exception to raise */
      unsigned long thread_id; /* Thread id where this tstate was created */
  
      int trash_delete_nesting;
      PyObject *trash_delete_later;
  
      /* Called when a thread state is deleted normally, but not when it
       * is destroyed after fork().
       * Pain:  to prevent rare but fatal shutdown errors (issue 18808),
       * Thread.join() must wait for the join'ed thread's tstate to be unlinked
       * from the tstate chain.  That happens at the end of a thread's life,
       * in pystate.c.
       * The obvious way doesn't quite work:  create a lock which the tstate
       * unlinking code releases, and have Thread.join() wait to acquire that
       * lock.  The problem is that we _are_ at the end of the thread's life:
       * if the thread holds the last reference to the lock, decref'ing the
       * lock will delete the lock, and that may trigger arbitrary Python code
       * if there's a weakref, with a callback, to the lock.  But by this time
       * _PyRuntime.gilstate.tstate_current is already NULL, so only the simplest
       * of C code can be allowed to run (in particular it must not be possible to
       * release the GIL).
       * So instead of holding the lock directly, the tstate holds a weakref to
       * the lock:  that's the value of on_delete_data below.  Decref'ing a
       * weakref is harmless.
       * on_delete points to _threadmodule.c's static release_sentinel() function.
       * After the tstate is unlinked, release_sentinel is called with the
       * weakref-to-lock (on_delete_data) argument, and release_sentinel releases
       * the indirectly held lock.
       */
      void (*on_delete)(void *);
      void *on_delete_data;
  
      int coroutine_origin_tracking_depth;
  
      PyObject *async_gen_firstiter;
      PyObject *async_gen_finalizer;
  
      PyObject *context;
      uint64_t context_ver;
  
      /* Unique thread state id. */
      uint64_t id;
  
      /* XXX signal handlers should also be here */
  
  };
  
  /* Get the current interpreter state.
  
     Issue a fatal error if there no current Python thread state or no current
     interpreter. It cannot return NULL.
  
     The caller must hold the GIL.*/
  PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_Get(void);
  
  PyAPI_FUNC(PyThreadState *) _PyThreadState_Prealloc(PyInterpreterState *);
  
  /* Similar to PyThreadState_Get(), but don't issue a fatal error
   * if it is NULL. */
  PyAPI_FUNC(PyThreadState *) _PyThreadState_UncheckedGet(void);
  
  /* PyGILState */
  
  /* Helper/diagnostic function - return 1 if the current thread
     currently holds the GIL, 0 otherwise.
  
     The function returns 1 if _PyGILState_check_enabled is non-zero. */
  PyAPI_FUNC(int) PyGILState_Check(void);
  
  /* Get the single PyInterpreterState used by this process' GILState
     implementation.
  
     This function doesn't check for error. Return NULL before _PyGILState_Init()
     is called and after _PyGILState_Fini() is called.
  
     See also _PyInterpreterState_Get() and _PyInterpreterState_GET_UNSAFE(). */
  PyAPI_FUNC(PyInterpreterState *) _PyGILState_GetInterpreterStateUnsafe(void);
  
  /* The implementation of sys._current_frames()  Returns a dict mapping
     thread id to that thread's current frame.
  */
  PyAPI_FUNC(PyObject *) _PyThread_CurrentFrames(void);
  
  /* Routines for advanced debuggers, requested by David Beazley.
     Don't use unless you know what you are doing! */
  PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Main(void);
  PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Head(void);
  PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Next(PyInterpreterState *);
  PyAPI_FUNC(PyThreadState *) PyInterpreterState_ThreadHead(PyInterpreterState *);
  PyAPI_FUNC(PyThreadState *) PyThreadState_Next(PyThreadState *);
  PyAPI_FUNC(void) PyThreadState_DeleteCurrent(void);
  
  typedef struct _frame *(*PyThreadFrameGetter)(PyThreadState *self_);
  
  /* cross-interpreter data */
  
  struct _xid;
  
  // _PyCrossInterpreterData is similar to Py_buffer as an effectively
  // opaque struct that holds data outside the object machinery.  This
  // is necessary to pass safely between interpreters in the same process.
  typedef struct _xid {
      // data is the cross-interpreter-safe derivation of a Python object
      // (see _PyObject_GetCrossInterpreterData).  It will be NULL if the
      // new_object func (below) encodes the data.
      void *data;
      // obj is the Python object from which the data was derived.  This
      // is non-NULL only if the data remains bound to the object in some
      // way, such that the object must be "released" (via a decref) when
      // the data is released.  In that case the code that sets the field,
      // likely a registered "crossinterpdatafunc", is responsible for
      // ensuring it owns the reference (i.e. incref).
      PyObject *obj;
      // interp is the ID of the owning interpreter of the original
      // object.  It corresponds to the active interpreter when
      // _PyObject_GetCrossInterpreterData() was called.  This should only
      // be set by the cross-interpreter machinery.
      //
      // We use the ID rather than the PyInterpreterState to avoid issues
      // with deleted interpreters.  Note that IDs are never re-used, so
      // each one will always correspond to a specific interpreter
      // (whether still alive or not).
      int64_t interp;
      // new_object is a function that returns a new object in the current
      // interpreter given the data.  The resulting object (a new
      // reference) will be equivalent to the original object.  This field
      // is required.
      PyObject *(*new_object)(struct _xid *);
      // free is called when the data is released.  If it is NULL then
      // nothing will be done to free the data.  For some types this is
      // okay (e.g. bytes) and for those types this field should be set
      // to NULL.  However, for most the data was allocated just for
      // cross-interpreter use, so it must be freed when
      // _PyCrossInterpreterData_Release is called or the memory will
      // leak.  In that case, at the very least this field should be set
      // to PyMem_RawFree (the default if not explicitly set to NULL).
      // The call will happen with the original interpreter activated.
      void (*free)(void *);
  } _PyCrossInterpreterData;
  
  PyAPI_FUNC(int) _PyObject_GetCrossInterpreterData(PyObject *, _PyCrossInterpreterData *);
  PyAPI_FUNC(PyObject *) _PyCrossInterpreterData_NewObject(_PyCrossInterpreterData *);
  PyAPI_FUNC(void) _PyCrossInterpreterData_Release(_PyCrossInterpreterData *);
  
  PyAPI_FUNC(int) _PyObject_CheckCrossInterpreterData(PyObject *);
  
  /* cross-interpreter data registry */
  
  typedef int (*crossinterpdatafunc)(PyObject *, struct _xid *);
  
  PyAPI_FUNC(int) _PyCrossInterpreterData_RegisterClass(PyTypeObject *, crossinterpdatafunc);
  PyAPI_FUNC(crossinterpdatafunc) _PyCrossInterpreterData_Lookup(PyObject *);
  
  #ifdef __cplusplus
  }
  #endif
  