Conteo de referencias
*********************

The functions and macros in this section are used for managing
reference counts of Python objects.

Py_ssize_t Py_REFCNT(PyObject *o)

   Get the reference count of the Python object *o*.

   Note that the returned value may not actually reflect how many
   references to the object are actually held.  For example, some
   objects are *immortal* and have a very high refcount that does not
   reflect the actual number of references.  Consequently, do not rely
   on the returned value to be accurate, other than a value of 0 or 1.

   Use the "Py_SET_REFCNT()" function to set an object reference
   count.

   Distinto en la versión 3.10: "Py_REFCNT()" is changed to the inline
   static function.

   Distinto en la versión 3.11: The parameter type is no longer const
   PyObject*.

void Py_SET_REFCNT(PyObject *o, Py_ssize_t refcnt)

   Set the object *o* reference counter to *refcnt*.

   On Python build with Free Threading, if *refcnt* is larger than
   "UINT32_MAX", the object is made *immortal*.

   This function has no effect on *immortal* objects.

   Added in version 3.9.

   Distinto en la versión 3.12: Immortal objects are not modified.

void Py_INCREF(PyObject *o)

   Indicate taking a new *strong reference* to object *o*, indicating
   it is in use and should not be destroyed.

   This function has no effect on *immortal* objects.

   Esta función se usa generalmente para convertir un *borrowed
   reference* en un *strong reference* en su lugar. La función
   "Py_NewRef()" se puede utilizar para crear un nuevo *strong
   reference*.

   When done using the object, release is by calling "Py_DECREF()".

   El objeto no debe ser "NULL"; si no está seguro de que no sea
   "NULL", use "Py_XINCREF()".

   Do not expect this function to actually modify *o* in any way. For
   at least **some objects**, this function has no effect.

   Distinto en la versión 3.12: Immortal objects are not modified.

void Py_XINCREF(PyObject *o)

   Similar to "Py_INCREF()", but the object *o* can be "NULL", in
   which case this has no effect.

   Ver también "Py_XNewRef()".

PyObject *Py_NewRef(PyObject *o)
    * Part of the Stable ABI since version 3.10.*

   Create a new *strong reference* to an object: call "Py_INCREF()" on
   *o* and return the object *o*.

   When the *strong reference* is no longer needed, "Py_DECREF()"
   should be called on it to release the reference.

   El objeto *o* no debe ser "NULL"; use "Py_XNewRef()" si *o* puede
   ser "NULL".

   Por ejemplo:

      Py_INCREF(obj);
      self->attr = obj;

   puede ser escrito como:

      self->attr = Py_NewRef(obj);

   Ver también "Py_INCREF()".

   Added in version 3.10.

PyObject *Py_XNewRef(PyObject *o)
    * Part of the Stable ABI since version 3.10.*

   Similar a "Py_NewRef()", pero el objeto *o* puede ser NULL.

   Si el objeto *o* es "NULL", la función solo retorna "NULL".

   Added in version 3.10.

void Py_DECREF(PyObject *o)

   Release a *strong reference* to object *o*, indicating the
   reference is no longer used.

   This function has no effect on *immortal* objects.

   Once the last *strong reference* is released (i.e. the object's
   reference count reaches 0), the object's type's deallocation
   function (which must not be "NULL") is invoked.

   Esta función se usa generalmente para eliminar un *strong
   reference* antes de salir de su alcance.

   El objeto no debe ser "NULL"; si no está seguro de que no sea
   "NULL", use "Py_XINCREF()".

   Do not expect this function to actually modify *o* in any way. For
   at least **some objects**, this function has no effect.

   Advertencia:

     The deallocation function can cause arbitrary Python code to be
     invoked (e.g. when a class instance with a "__del__()" method is
     deallocated).  While exceptions in such code are not propagated,
     the executed code has free access to all Python global variables.
     This means that any object that is reachable from a global
     variable should be in a consistent state before "Py_DECREF()" is
     invoked.  For example, code to delete an object from a list
     should copy a reference to the deleted object in a temporary
     variable, update the list data structure, and then call
     "Py_DECREF()" for the temporary variable.

   Distinto en la versión 3.12: Immortal objects are not modified.

void Py_XDECREF(PyObject *o)

   Similar to "Py_DECREF()", but the object *o* can be "NULL", in
   which case this has no effect. The same warning from "Py_DECREF()"
   applies here as well.

void Py_CLEAR(PyObject *o)

   Release a *strong reference* for object *o*. The object may be
   "NULL", in which case the macro has no effect; otherwise the effect
   is the same as for "Py_DECREF()", except that the argument is also
   set to "NULL".  The warning for "Py_DECREF()" does not apply with
   respect to the object passed because the macro carefully uses a
   temporary variable and sets the argument to "NULL" before releasing
   the reference.

   It is a good idea to use this macro whenever releasing a reference
   to an object that might be traversed during garbage collection.

   Distinto en la versión 3.12: The macro argument is now only
   evaluated once. If the argument has side effects, these are no
   longer duplicated.

void Py_IncRef(PyObject *o)
    * Part of the Stable ABI.*

   Indicate taking a new *strong reference* to object *o*. A function
   version of "Py_XINCREF()". It can be used for runtime dynamic
   embedding of Python.

void Py_DecRef(PyObject *o)
    * Part of the Stable ABI.*

   Release a *strong reference* to object *o*. A function version of
   "Py_XDECREF()". It can be used for runtime dynamic embedding of
   Python.

Py_SETREF(dst, src)

   Macro safely releasing a *strong reference* to object *dst* and
   setting *dst* to *src*.

   As in case of "Py_CLEAR()", "the obvious" code can be deadly:

      Py_DECREF(dst);
      dst = src;

   The safe way is:

      Py_SETREF(dst, src);

   That arranges to set *dst* to *src* _before_ releasing the
   reference to the old value of *dst*, so that any code triggered as
   a side-effect of *dst* getting torn down no longer believes *dst*
   points to a valid object.

   Added in version 3.6.

   Distinto en la versión 3.12: The macro arguments are now only
   evaluated once. If an argument has side effects, these are no
   longer duplicated.

Py_XSETREF(dst, src)

   Variant of "Py_SETREF" macro that uses "Py_XDECREF()" instead of
   "Py_DECREF()".

   Added in version 3.6.

   Distinto en la versión 3.12: The macro arguments are now only
   evaluated once. If an argument has side effects, these are no
   longer duplicated.
