Issue python#23406: Clarify documentation on multiplying a sequence

Patch from Matheus Vieira Portela.

Author: Martin Panter

Doc/faq/programming.rst

@@ -1164,6 +1164,8 @@ analogue of lisp car is ``lisp_list[0]`` and the analogue of cdr is
 usually a lot slower than using Python lists.
 
 
+.. _faq-multidimensional-list:
+
 How do I create a multidimensional list?
 ----------------------------------------
 

Doc/library/stdtypes.rst

@@ -854,8 +854,8 @@ operations have the same priority as the corresponding numeric operations.
 | ``s + t``                | the concatenation of *s* and   | (6)(7)   |
 |                          | *t*                            |          |
 +--------------------------+--------------------------------+----------+
-| ``s * n`` or             | *n* shallow copies of *s*      | (2)(7)   |
-| ``n * s``                | concatenated                   |          |
+| ``s * n`` or             | equivalent to adding *s* to    | (2)(7)   |
+| ``n * s``                | itself *n* times               |          |
 +--------------------------+--------------------------------+----------+
 | ``s[i]``                 | *i*\ th item of *s*, origin 0  | \(3)     |
 +--------------------------+--------------------------------+----------+
@@ -897,9 +897,9 @@ Notes:
 
 (2)
    Values of *n* less than ``0`` are treated as ``0`` (which yields an empty
-   sequence of the same type as *s*).  Note also that the copies are shallow;
-   nested structures are not copied.  This often haunts new Python programmers;
-   consider::
+   sequence of the same type as *s*).  Note that items in the sequence *s*
+   are not copied; they are referenced multiple times.  This often haunts
+   new Python programmers; consider::
 
       >>> lists = [[]] * 3
       >>> lists
@@ -909,7 +909,7 @@ Notes:
       [[3], [3], [3]]
 
    What has happened is that ``[[]]`` is a one-element list containing an empty
-   list, so all three elements of ``[[]] * 3`` are (pointers to) this single empty
+   list, so all three elements of ``[[]] * 3`` are references to this single empty
    list.  Modifying any of the elements of ``lists`` modifies this single list.
    You can create a list of different lists this way::
 
@@ -920,6 +920,9 @@ Notes:
       >>> lists
       [[3], [5], [7]]
 
+   Further explanation is available in the FAQ entry
+   :ref:`faq-multidimensional-list`.
+
 (3)
    If *i* or *j* is negative, the index is relative to the end of the string:
    ``len(s) + i`` or ``len(s) + j`` is substituted.  But note that ``-0`` is

Misc/ACKS

@@ -1097,6 +1097,7 @@ Martin Pool
 Iustin Pop
 Claudiu Popa
 John Popplewell
+Matheus Vieira Portela
 Davin Potts
 Guillaume Pratte
 Florian Preinstorfer