Sequence Protocol
*****************

int PySequence_Check(PyObject *o)
    * Part of the Stable ABI.*

   Return "1" if the object provides the sequence protocol, and "0"
   otherwise. Note that it returns "1" for Python classes with a
   "__getitem__()" method, unless they are "dict" subclasses, since in
   general it is impossible to determine what type of keys the class
   supports.  This function always succeeds.

Py_ssize_t PySequence_Size(PyObject *o)
Py_ssize_t PySequence_Length(PyObject *o)
    * Part of the Stable ABI.*

   Returns the number of objects in sequence *o* on success, and "-1"
   on failure.  This is equivalent to the Python expression "len(o)".

PyObject *PySequence_Concat(PyObject *o1, PyObject *o2)
    *Return value: New reference.** Part of the Stable ABI.*

   Return the concatenation of *o1* and *o2* on success, and "NULL" on
   failure. This is the equivalent of the Python expression "o1 + o2".

PyObject *PySequence_Repeat(PyObject *o, Py_ssize_t count)
    *Return value: New reference.** Part of the Stable ABI.*

   Return the result of repeating sequence object *o* *count* times,
   or "NULL" on failure.  This is the equivalent of the Python
   expression "o * count".

PyObject *PySequence_InPlaceConcat(PyObject *o1, PyObject *o2)
    *Return value: New reference.** Part of the Stable ABI.*

   Return the concatenation of *o1* and *o2* on success, and "NULL" on
   failure. The operation is done *in-place* when *o1* supports it.
   This is the equivalent of the Python expression "o1 += o2".

PyObject *PySequence_InPlaceRepeat(PyObject *o, Py_ssize_t count)
    *Return value: New reference.** Part of the Stable ABI.*

   Return the result of repeating sequence object *o* *count* times,
   or "NULL" on failure.  The operation is done *in-place* when *o*
   supports it.  This is the equivalent of the Python expression "o *=
   count".

PyObject *PySequence_GetItem(PyObject *o, Py_ssize_t i)
    *Return value: New reference.** Part of the Stable ABI.*

   Return the *i*th element of *o*, or "NULL" on failure. This is the
   equivalent of the Python expression "o[i]".

PyObject *PySequence_GetSlice(PyObject *o, Py_ssize_t i1, Py_ssize_t i2)
    *Return value: New reference.** Part of the Stable ABI.*

   Return the slice of sequence object *o* between *i1* and *i2*, or
   "NULL" on failure. This is the equivalent of the Python expression
   "o[i1:i2]".

int PySequence_SetItem(PyObject *o, Py_ssize_t i, PyObject *v)
    * Part of the Stable ABI.*

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

   If *v* is "NULL", the element is deleted, but this feature is
   deprecated in favour of using "PySequence_DelItem()".

int PySequence_DelItem(PyObject *o, Py_ssize_t i)
    * Part of the Stable ABI.*

   Delete the *i*th element of object *o*.  Returns "-1" on failure.
   This is the equivalent of the Python statement "del o[i]".

int PySequence_SetSlice(PyObject *o, Py_ssize_t i1, Py_ssize_t i2, PyObject *v)
    * Part of the Stable ABI.*

   Assign the sequence object *v* to the slice in sequence object *o*
   from *i1* to *i2*.  This is the equivalent of the Python statement
   "o[i1:i2] = v".

int PySequence_DelSlice(PyObject *o, Py_ssize_t i1, Py_ssize_t i2)
    * Part of the Stable ABI.*

   Delete the slice in sequence object *o* from *i1* to *i2*.  Returns
   "-1" on failure.  This is the equivalent of the Python statement
   "del o[i1:i2]".

Py_ssize_t PySequence_Count(PyObject *o, PyObject *value)
    * Part of the Stable ABI.*

   Return the number of occurrences of *value* in *o*, that is, return
   the number of keys for which "o[key] == value".  On failure, return
   "-1".  This is equivalent to the Python expression
   "o.count(value)".

int PySequence_Contains(PyObject *o, PyObject *value)
    * Part of the Stable ABI.*

   Determine if *o* contains *value*.  If an item in *o* is equal to
   *value*, return "1", otherwise return "0". On error, return "-1".
   This is equivalent to the Python expression "value in o".

Py_ssize_t PySequence_Index(PyObject *o, PyObject *value)
    * Part of the Stable ABI.*

   Return the first index *i* for which "o[i] == value".  On error,
   return "-1".    This is equivalent to the Python expression
   "o.index(value)".

PyObject *PySequence_List(PyObject *o)
    *Return value: New reference.** Part of the Stable ABI.*

   Return a list object with the same contents as the sequence or
   iterable *o*, or "NULL" on failure.  The returned list is
   guaranteed to be new.  This is equivalent to the Python expression
   "list(o)".

PyObject *PySequence_Tuple(PyObject *o)
    *Return value: New reference.** Part of the Stable ABI.*

   Return a tuple object with the same contents as the sequence or
   iterable *o*, or "NULL" on failure.  If *o* is a tuple, a new
   reference will be returned, otherwise a tuple will be constructed
   with the appropriate contents.  This is equivalent to the Python
   expression "tuple(o)".

PyObject *PySequence_Fast(PyObject *o, const char *m)
    *Return value: New reference.** Part of the Stable ABI.*

   Return the sequence or iterable *o* as an object usable by the
   other "PySequence_Fast*" family of functions. If the object is not
   a sequence or iterable, raises "TypeError" with *m* as the message
   text. Returns "NULL" on failure.

   The "PySequence_Fast*" functions are thus named because they assume
   *o* is a "PyTupleObject" or a "PyListObject" and access the data
   fields of *o* directly.

   As a CPython implementation detail, if *o* is already a sequence or
   list, it will be returned.

Py_ssize_t PySequence_Fast_GET_SIZE(PyObject *o)

   Returns the length of *o*, assuming that *o* was returned by
   "PySequence_Fast()" and that *o* is not "NULL".  The size can also
   be retrieved by calling "PySequence_Size()" on *o*, but
   "PySequence_Fast_GET_SIZE()" is faster because it can assume *o* is
   a list or tuple.

PyObject *PySequence_Fast_GET_ITEM(PyObject *o, Py_ssize_t i)
    *Return value: Borrowed reference.*

   Return the *i*th element of *o*, assuming that *o* was returned by
   "PySequence_Fast()", *o* is not "NULL", and that *i* is within
   bounds.

PyObject **PySequence_Fast_ITEMS(PyObject *o)

   Return the underlying array of PyObject pointers.  Assumes that *o*
   was returned by "PySequence_Fast()" and *o* is not "NULL".

   Note, if a list gets resized, the reallocation may relocate the
   items array. So, only use the underlying array pointer in contexts
   where the sequence cannot change.

PyObject *PySequence_ITEM(PyObject *o, Py_ssize_t i)
    *Return value: New reference.*

   Return the *i*th element of *o* or "NULL" on failure. Faster form
   of "PySequence_GetItem()" but without checking that
   "PySequence_Check()" on *o* is true and without adjustment for
   negative indices.
