[3.6] bpo-29751: Improve PyLong_FromString documentation (GH-915) (#1266)
(cherry picked from commit 26896f2832324dde85cdd63d525571ca669f6f0b)
diff --git a/Doc/c-api/long.rst b/Doc/c-api/long.rst
index f592cb6..f50680b 100644
--- a/Doc/c-api/long.rst
+++ b/Doc/c-api/long.rst
@@ -85,13 +85,12 @@
Return a new :c:type:`PyLongObject` based on the string value in *str*, which
is interpreted according to the radix in *base*. If *pend* is non-*NULL*,
*\*pend* will point to the first character in *str* which follows the
- representation of the number. If *base* is ``0``, the radix will be
- determined based on the leading characters of *str*: if *str* starts with
- ``'0x'`` or ``'0X'``, radix 16 will be used; if *str* starts with ``'0o'`` or
- ``'0O'``, radix 8 will be used; if *str* starts with ``'0b'`` or ``'0B'``,
- radix 2 will be used; otherwise radix 10 will be used. If *base* is not
- ``0``, it must be between ``2`` and ``36``, inclusive. Leading spaces are
- ignored. If there are no digits, :exc:`ValueError` will be raised.
+ representation of the number. If *base* is ``0``, *str* is interpreted using
+ the :ref:`integers` definition; in this case, leading zeros in a
+ non-zero decimal number raises a :exc:`ValueError`. If *base* is not ``0``,
+ it must be between ``2`` and ``36``, inclusive. Leading spaces and single
+ underscores after a base specifier and between digits are ignored. If there
+ are no digits, :exc:`ValueError` will be raised.
.. c:function:: PyObject* PyLong_FromUnicode(Py_UNICODE *u, Py_ssize_t length, int base)