diff -r 7ce22d0899e4 Doc/library/stdtypes.rst
--- a/Doc/library/stdtypes.rst	Fri Mar 14 21:54:41 2014 -0500
+++ b/Doc/library/stdtypes.rst	Thu Dec 18 04:11:09 2014 +0000
@@ -1907,22 +1907,24 @@
         "They're Bill's Friends."
 
 
-.. method:: str.translate(map)
-
-   Return a copy of the *s* where all characters have been mapped through the
-   *map* which must be a dictionary of Unicode ordinals (integers) to Unicode
-   ordinals, strings or ``None``.  Unmapped characters are left untouched.
-   Characters mapped to ``None`` are deleted.
-
-   You can use :meth:`str.maketrans` to create a translation map from
+.. method:: str.translate(table)
+
+   Return a copy of the string in which each character has been
+   mapped through the given translation table.  The table must be
+   a subscriptable object, for instance a dictionary or list.  When
+   subscripted (indexed) by a Unicode ordinal (an integer),
+   the table object can:
+
+   * return a Unicode ordinal or a string, to
+     map the character to one or more other characters
+   * return ``None``, to delete the character from the return string
+   * raise a :exc:`LookupError` (possibly an instance of
+     subclass :exc:`KeyError` or :exc:`IndexError`), to
+     map the character to itself
+
+   You can use :meth:`str.maketrans` to create a translation table from
    character-to-character mappings in different formats.
 
-   .. note::
-
-      An even more flexible approach is to create a custom character mapping
-      codec using the :mod:`codecs` module (see :mod:`encodings.cp1251` for an
-      example).
-
 
 .. method:: str.upper()
 
diff -r 7ce22d0899e4 Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Fri Mar 14 21:54:41 2014 -0500
+++ b/Objects/unicodeobject.c	Thu Dec 18 04:11:09 2014 +0000
@@ -13035,11 +13035,12 @@
 PyDoc_STRVAR(translate__doc__,
              "S.translate(table) -> str\n\
 \n\
-Return a copy of the string S, where all characters have been mapped\n\
-through the given translation table, which must be a mapping of\n\
-Unicode ordinals to Unicode ordinals, strings, or None.\n\
-Unmapped characters are left untouched. Characters mapped to None\n\
-are deleted.");
+Return a copy of the string S in which each character has been mapped\n\
+through the given translation table. The table must be a subscriptable\n\
+object, for instance a dictionary or list, mapping Unicode ordinals to\n\
+Unicode ordinals, strings, or None. If a character is not in the table,\n\
+the subscript operation should raise LookupError, and the character is\n\
+left untouched. Characters mapped to None are deleted.");
 
 static PyObject*
 unicode_translate(PyObject *self, PyObject *table)