Issue #18452: fix several "occurrence" typos (reported by Févry Thibault).

Doc/howto/argparse.rst

@@ -468,7 +468,7 @@ verbosity argument (check the output of ``python --help``)::
        print(answer)
 
 We have introduced another action, "count",
-to count the number of occurences of a specific optional arguments:
+to count the number of occurrences of a specific optional arguments:
 
 .. code-block:: sh
 

Doc/library/configparser.rst

@@ -539,7 +539,7 @@ the :meth:`__init__` options:
 * *delimiters*, default value: ``('=', ':')``
 
   Delimiters are substrings that delimit keys from values within a section. The
-  first occurence of a delimiting substring on a line is considered a delimiter.
+  first occurrence of a delimiting substring on a line is considered a delimiter.
   This means values (but not keys) can contain the delimiters.
 
   See also the *space_around_delimiters* argument to

Doc/library/stdtypes.rst

@@ -871,11 +871,11 @@ operations have the same priority as the corresponding numeric operations.
 +--------------------------+--------------------------------+----------+
 | ``max(s)``               | largest item of *s*            |          |
 +--------------------------+--------------------------------+----------+
-| ``s.index(x[, i[, j]])`` | index of the first occurence   | \(8)     |
+| ``s.index(x[, i[, j]])`` | index of the first occurrence  | \(8)     |
 |                          | of *x* in *s* (at or after     |          |
 |                          | index *i* and before index *j*)|          |
 +--------------------------+--------------------------------+----------+
-| ``s.count(x)``           | total number of occurences of  |          |
+| ``s.count(x)``           | total number of occurrences of |          |
 |                          | *x* in *s*                     |          |
 +--------------------------+--------------------------------+----------+