Object Protocol
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PyObject* Py_NotImplemented

   The "NotImplemented" singleton, used to signal that an operation is
   not implemented for the given type combination.

Py_RETURN_NOTIMPLEMENTED

   Properly handle returning "Py_NotImplemented" from within a C
   function (that is, increment the reference count of NotImplemented
   and return it).

int PyObject_Print(PyObject *o, FILE *fp, int flags)

   Print an object *o*, on file *fp*.  Returns "-1" on error.  The
   flags argument is used to enable certain printing options.  The
   only option currently supported is "Py_PRINT_RAW"; if given, the
   "str()" of the object is written instead of the "repr()".

int PyObject_HasAttr(PyObject *o, PyObject *attr_name)

   Returns "1" if *o* has the attribute *attr_name*, and "0"
   otherwise.  This is equivalent to the Python expression "hasattr(o,
   attr_name)".  This function always succeeds.

   Note that exceptions which occur while calling "__getattr__()" and
   "__getattribute__()" methods will get suppressed. To get error
   reporting use "PyObject_GetAttr()" instead.

int PyObject_HasAttrString(PyObject *o, const char *attr_name)

   Returns "1" if *o* has the attribute *attr_name*, and "0"
   otherwise.  This is equivalent to the Python expression "hasattr(o,
   attr_name)".  This function always succeeds.

   Note that exceptions which occur while calling "__getattr__()" and
   "__getattribute__()" methods and creating a temporary string object
   will get suppressed. To get error reporting use
   "PyObject_GetAttrString()" instead.

PyObject* PyObject_GetAttr(PyObject *o, PyObject *attr_name)
    *Return value: New reference.*

   Retrieve an attribute named *attr_name* from object *o*. Returns
   the attribute value on success, or "NULL" on failure.  This is the
   equivalent of the Python expression "o.attr_name".

PyObject* PyObject_GetAttrString(PyObject *o, const char *attr_name)
    *Return value: New reference.*

   Retrieve an attribute named *attr_name* from object *o*. Returns
   the attribute value on success, or "NULL" on failure. This is the
   equivalent of the Python expression "o.attr_name".

PyObject* PyObject_GenericGetAttr(PyObject *o, PyObject *name)
    *Return value: New reference.*

   Generic attribute getter function that is meant to be put into a
   type object’s "tp_getattro" slot.  It looks for a descriptor in the
   dictionary of classes in the object’s MRO as well as an attribute
   in the object’s "__dict__" (if present).  As outlined in
   Implementing Descriptors, data descriptors take preference over
   instance attributes, while non-data descriptors don’t.  Otherwise,
   an "AttributeError" is raised.

int PyObject_SetAttr(PyObject *o, PyObject *attr_name, PyObject *v)

   Set the value of the attribute named *attr_name*, for object *o*,
   to the value *v*. Raise an exception and return "-1" on failure;
   return "0" on success.  This is the equivalent of the Python
   statement "o.attr_name = v".

   If *v* is "NULL", the attribute is deleted, however this feature is
   deprecated in favour of using "PyObject_DelAttr()".

int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v)

   Set the value of the attribute named *attr_name*, for object *o*,
   to the value *v*. Raise an exception and return "-1" on failure;
   return "0" on success.  This is the equivalent of the Python
   statement "o.attr_name = v".

   If *v* is "NULL", the attribute is deleted, however this feature is
   deprecated in favour of using "PyObject_DelAttrString()".

int PyObject_GenericSetAttr(PyObject *o, PyObject *name, PyObject *value)

   Generic attribute setter and deleter function that is meant to be
   put into a type object’s "tp_setattro" slot.  It looks for a data
   descriptor in the dictionary of classes in the object’s MRO, and if
   found it takes preference over setting or deleting the attribute in
   the instance dictionary. Otherwise, the attribute is set or deleted
   in the object’s "__dict__" (if present). On success, "0" is
   returned, otherwise an "AttributeError" is raised and "-1" is
   returned.

int PyObject_DelAttr(PyObject *o, PyObject *attr_name)

   Delete attribute named *attr_name*, for object *o*. Returns "-1" on
   failure. This is the equivalent of the Python statement "del
   o.attr_name".

int PyObject_DelAttrString(PyObject *o, const char *attr_name)

   Delete attribute named *attr_name*, for object *o*. Returns "-1" on
   failure. This is the equivalent of the Python statement "del
   o.attr_name".

PyObject* PyObject_GenericGetDict(PyObject *o, void *context)
    *Return value: New reference.*

   A generic implementation for the getter of a "__dict__" descriptor.
   It creates the dictionary if necessary.

   New in version 3.3.

int PyObject_GenericSetDict(PyObject *o, void *context)

   A generic implementation for the setter of a "__dict__" descriptor.
   This implementation does not allow the dictionary to be deleted.

   New in version 3.3.

PyObject* PyObject_RichCompare(PyObject *o1, PyObject *o2, int opid)
    *Return value: New reference.*

   Compare the values of *o1* and *o2* using the operation specified
   by *opid*, which must be one of "Py_LT", "Py_LE", "Py_EQ", "Py_NE",
   "Py_GT", or "Py_GE", corresponding to "<", "<=", "==", "!=", ">",
   or ">=" respectively. This is the equivalent of the Python
   expression "o1 op o2", where "op" is the operator corresponding to
   *opid*. Returns the value of the comparison on success, or "NULL"
   on failure.

int PyObject_RichCompareBool(PyObject *o1, PyObject *o2, int opid)

   Compare the values of *o1* and *o2* using the operation specified
   by *opid*, which must be one of "Py_LT", "Py_LE", "Py_EQ", "Py_NE",
   "Py_GT", or "Py_GE", corresponding to "<", "<=", "==", "!=", ">",
   or ">=" respectively. Returns "-1" on error, "0" if the result is
   false, "1" otherwise. This is the equivalent of the Python
   expression "o1 op o2", where "op" is the operator corresponding to
   *opid*.

Note: If *o1* and *o2* are the same object,
  "PyObject_RichCompareBool()" will always return "1" for "Py_EQ" and
  "0" for "Py_NE".

PyObject* PyObject_Repr(PyObject *o)
    *Return value: New reference.*

   Compute a string representation of object *o*.  Returns the string
   representation on success, "NULL" on failure.  This is the
   equivalent of the Python expression "repr(o)".  Called by the
   "repr()" built-in function.

   Changed in version 3.4: This function now includes a debug
   assertion to help ensure that it does not silently discard an
   active exception.

PyObject* PyObject_ASCII(PyObject *o)
    *Return value: New reference.*

   As "PyObject_Repr()", compute a string representation of object
   *o*, but escape the non-ASCII characters in the string returned by
   "PyObject_Repr()" with "\x", "\u" or "\U" escapes.  This generates
   a string similar to that returned by "PyObject_Repr()" in Python 2.
   Called by the "ascii()" built-in function.

PyObject* PyObject_Str(PyObject *o)
    *Return value: New reference.*

   Compute a string representation of object *o*.  Returns the string
   representation on success, "NULL" on failure.  This is the
   equivalent of the Python expression "str(o)".  Called by the
   "str()" built-in function and, therefore, by the "print()"
   function.

   Changed in version 3.4: This function now includes a debug
   assertion to help ensure that it does not silently discard an
   active exception.

PyObject* PyObject_Bytes(PyObject *o)
    *Return value: New reference.*

   Compute a bytes representation of object *o*.  "NULL" is returned
   on failure and a bytes object on success.  This is equivalent to
   the Python expression "bytes(o)", when *o* is not an integer.
   Unlike "bytes(o)", a TypeError is raised when *o* is an integer
   instead of a zero-initialized bytes object.

int PyObject_IsSubclass(PyObject *derived, PyObject *cls)

   Return "1" if the class *derived* is identical to or derived from
   the class *cls*, otherwise return "0".  In case of an error, return
   "-1".

   If *cls* is a tuple, the check will be done against every entry in
   *cls*. The result will be "1" when at least one of the checks
   returns "1", otherwise it will be "0".

   If *cls* has a "__subclasscheck__()" method, it will be called to
   determine the subclass status as described in **PEP 3119**.
   Otherwise, *derived* is a subclass of *cls* if it is a direct or
   indirect subclass, i.e. contained in "cls.__mro__".

   Normally only class objects, i.e. instances of "type" or a derived
   class, are considered classes.  However, objects can override this
   by having a "__bases__" attribute (which must be a tuple of base
   classes).

int PyObject_IsInstance(PyObject *inst, PyObject *cls)

   Return "1" if *inst* is an instance of the class *cls* or a
   subclass of *cls*, or "0" if not.  On error, returns "-1" and sets
   an exception.

   If *cls* is a tuple, the check will be done against every entry in
   *cls*. The result will be "1" when at least one of the checks
   returns "1", otherwise it will be "0".

   If *cls* has a "__instancecheck__()" method, it will be called to
   determine the subclass status as described in **PEP 3119**.
   Otherwise, *inst* is an instance of *cls* if its class is a
   subclass of *cls*.

   An instance *inst* can override what is considered its class by
   having a "__class__" attribute.

   An object *cls* can override if it is considered a class, and what
   its base classes are, by having a "__bases__" attribute (which must
   be a tuple of base classes).

int PyCallable_Check(PyObject *o)

   Determine if the object *o* is callable.  Return "1" if the object
   is callable and "0" otherwise.  This function always succeeds.

PyObject* PyObject_Call(PyObject *callable, PyObject *args, PyObject *kwargs)
    *Return value: New reference.*

   Call a callable Python object *callable*, with arguments given by
   the tuple *args*, and named arguments given by the dictionary
   *kwargs*.

   *args* must not be "NULL", use an empty tuple if no arguments are
   needed. If no named arguments are needed, *kwargs* can be "NULL".

   Return the result of the call on success, or raise an exception and
   return "NULL" on failure.

   This is the equivalent of the Python expression: "callable(*args,
   **kwargs)".

PyObject* PyObject_CallObject(PyObject *callable, PyObject *args)
    *Return value: New reference.*

   Call a callable Python object *callable*, with arguments given by
   the tuple *args*.  If no arguments are needed, then *args* can be
   "NULL".

   Return the result of the call on success, or raise an exception and
   return "NULL" on failure.

   This is the equivalent of the Python expression: "callable(*args)".

PyObject* PyObject_CallFunction(PyObject *callable, const char *format, ...)
    *Return value: New reference.*

   Call a callable Python object *callable*, with a variable number of
   C arguments. The C arguments are described using a
   "Py_BuildValue()" style format string.  The format can be "NULL",
   indicating that no arguments are provided.

   Return the result of the call on success, or raise an exception and
   return "NULL" on failure.

   This is the equivalent of the Python expression: "callable(*args)".

   Note that if you only pass "PyObject *" args,
   "PyObject_CallFunctionObjArgs()" is a faster alternative.

   Changed in version 3.4: The type of *format* was changed from "char
   *".

PyObject* PyObject_CallMethod(PyObject *obj, const char *name, const char *format, ...)
    *Return value: New reference.*

   Call the method named *name* of object *obj* with a variable number
   of C arguments.  The C arguments are described by a
   "Py_BuildValue()" format string that should  produce a tuple.

   The format can be "NULL", indicating that no arguments are
   provided.

   Return the result of the call on success, or raise an exception and
   return "NULL" on failure.

   This is the equivalent of the Python expression: "obj.name(arg1,
   arg2, ...)".

   Note that if you only pass "PyObject *" args,
   "PyObject_CallMethodObjArgs()" is a faster alternative.

   Changed in version 3.4: The types of *name* and *format* were
   changed from "char *".

PyObject* PyObject_CallFunctionObjArgs(PyObject *callable, ..., NULL)
    *Return value: New reference.*

   Call a callable Python object *callable*, with a variable number of
   "PyObject*" arguments.  The arguments are provided as a variable
   number of parameters followed by "NULL".

   Return the result of the call on success, or raise an exception and
   return "NULL" on failure.

   This is the equivalent of the Python expression: "callable(arg1,
   arg2, ...)".

PyObject* PyObject_CallMethodObjArgs(PyObject *obj, PyObject *name, ..., NULL)
    *Return value: New reference.*

   Calls a method of the Python object *obj*, where the name of the
   method is given as a Python string object in *name*.  It is called
   with a variable number of "PyObject*" arguments.  The arguments are
   provided as a variable number of parameters followed by "NULL".

   Return the result of the call on success, or raise an exception and
   return "NULL" on failure.

PyObject* _PyObject_Vectorcall(PyObject *callable, PyObject *const *args, size_t nargsf, PyObject *kwnames)

   Call a callable Python object *callable*, using "vectorcall" if
   possible.

   *args* is a C array with the positional arguments.

   *nargsf* is the number of positional arguments plus optionally the
   flag "PY_VECTORCALL_ARGUMENTS_OFFSET" (see below). To get actual
   number of arguments, use "PyVectorcall_NARGS(nargsf)".

   *kwnames* can be either "NULL" (no keyword arguments) or a tuple of
   keyword names. In the latter case, the values of the keyword
   arguments are stored in *args* after the positional arguments. The
   number of keyword arguments does not influence *nargsf*.

   *kwnames* must contain only objects of type "str" (not a subclass),
   and all keys must be unique.

   Return the result of the call on success, or raise an exception and
   return "NULL" on failure.

   This uses the vectorcall protocol if the callable supports it;
   otherwise, the arguments are converted to use "tp_call".

   Note: This function is provisional and expected to become public
     in Python 3.9, with a different name and, possibly, changed
     semantics. If you use the function, plan for updating your code
     for Python 3.9.

   New in version 3.8.

PY_VECTORCALL_ARGUMENTS_OFFSET

   If set in a vectorcall *nargsf* argument, the callee is allowed to
   temporarily change "args[-1]". In other words, *args* points to
   argument 1 (not 0) in the allocated vector. The callee must restore
   the value of "args[-1]" before returning.

   Whenever they can do so cheaply (without additional allocation),
   callers are encouraged to use "PY_VECTORCALL_ARGUMENTS_OFFSET".
   Doing so will allow callables such as bound methods to make their
   onward calls (which include a prepended *self* argument) cheaply.

   New in version 3.8.

Py_ssize_t PyVectorcall_NARGS(size_t nargsf)

   Given a vectorcall *nargsf* argument, return the actual number of
   arguments. Currently equivalent to "nargsf &
   ~PY_VECTORCALL_ARGUMENTS_OFFSET".

   New in version 3.8.

PyObject* _PyObject_FastCallDict(PyObject *callable, PyObject *const *args, size_t nargsf, PyObject *kwdict)

   Same as "_PyObject_Vectorcall()" except that the keyword arguments
   are passed as a dictionary in *kwdict*. This may be "NULL" if there
   are no keyword arguments.

   For callables supporting "vectorcall", the arguments are internally
   converted to the vectorcall convention. Therefore, this function
   adds some overhead compared to "_PyObject_Vectorcall()". It should
   only be used if the caller already has a dictionary ready to use.

   Note: This function is provisional and expected to become public
     in Python 3.9, with a different name and, possibly, changed
     semantics. If you use the function, plan for updating your code
     for Python 3.9.

   New in version 3.8.

Py_hash_t PyObject_Hash(PyObject *o)

   Compute and return the hash value of an object *o*.  On failure,
   return "-1". This is the equivalent of the Python expression
   "hash(o)".

   Changed in version 3.2: The return type is now Py_hash_t.  This is
   a signed integer the same size as Py_ssize_t.

Py_hash_t PyObject_HashNotImplemented(PyObject *o)

   Set a "TypeError" indicating that "type(o)" is not hashable and
   return "-1". This function receives special treatment when stored
   in a "tp_hash" slot, allowing a type to explicitly indicate to the
   interpreter that it is not hashable.

int PyObject_IsTrue(PyObject *o)

   Returns "1" if the object *o* is considered to be true, and "0"
   otherwise. This is equivalent to the Python expression "not not o".
   On failure, return "-1".

int PyObject_Not(PyObject *o)

   Returns "0" if the object *o* is considered to be true, and "1"
   otherwise. This is equivalent to the Python expression "not o".  On
   failure, return "-1".

PyObject* PyObject_Type(PyObject *o)
    *Return value: New reference.*

   When *o* is non-"NULL", returns a type object corresponding to the
   object type of object *o*. On failure, raises "SystemError" and
   returns "NULL".  This is equivalent to the Python expression
   "type(o)". This function increments the reference count of the
   return value. There’s really no reason to use this function instead
   of the common expression "o->ob_type", which returns a pointer of
   type "PyTypeObject*", except when the incremented reference count
   is needed.

int PyObject_TypeCheck(PyObject *o, PyTypeObject *type)

   Return true if the object *o* is of type *type* or a subtype of
   *type*.  Both parameters must be non-"NULL".

Py_ssize_t PyObject_Size(PyObject *o)
Py_ssize_t PyObject_Length(PyObject *o)

   Return the length of object *o*.  If the object *o* provides either
   the sequence and mapping protocols, the sequence length is
   returned.  On error, "-1" is returned.  This is the equivalent to
   the Python expression "len(o)".

Py_ssize_t PyObject_LengthHint(PyObject *o, Py_ssize_t default)

   Return an estimated length for the object *o*. First try to return
   its actual length, then an estimate using "__length_hint__()", and
   finally return the default value. On error return "-1". This is the
   equivalent to the Python expression "operator.length_hint(o,
   default)".

   New in version 3.4.

PyObject* PyObject_GetItem(PyObject *o, PyObject *key)
    *Return value: New reference.*

   Return element of *o* corresponding to the object *key* or "NULL"
   on failure. This is the equivalent of the Python expression
   "o[key]".

int PyObject_SetItem(PyObject *o, PyObject *key, PyObject *v)

   Map the object *key* to the value *v*.  Raise an exception and
   return "-1" on failure; return "0" on success.  This is the
   equivalent of the Python statement "o[key] = v".  This function
   *does not* steal a reference to *v*.

int PyObject_DelItem(PyObject *o, PyObject *key)

   Remove the mapping for the object *key* from the object *o*.
   Return "-1" on failure.  This is equivalent to the Python statement
   "del o[key]".

PyObject* PyObject_Dir(PyObject *o)
    *Return value: New reference.*

   This is equivalent to the Python expression "dir(o)", returning a
   (possibly empty) list of strings appropriate for the object
   argument, or "NULL" if there was an error.  If the argument is
   "NULL", this is like the Python "dir()", returning the names of the
   current locals; in this case, if no execution frame is active then
   "NULL" is returned but "PyErr_Occurred()" will return false.

PyObject* PyObject_GetIter(PyObject *o)
    *Return value: New reference.*

   This is equivalent to the Python expression "iter(o)". It returns a
   new iterator for the object argument, or the object  itself if the
   object is already an iterator.  Raises "TypeError" and returns
   "NULL" if the object cannot be iterated.
