Fix grammar, typos and markup in documentation and code comments

* Indent versionchanged at method level, not class level
* Mark up ``--help`` to avoid generating an en dash
* Use forward slash in Unix command line with a dollar sign ($) prompt

Doc/library/argparse.rst

@@ -174,7 +174,7 @@ ArgumentParser objects
    * conflict_handler_ - The strategy for resolving conflicting optionals
      (usually unnecessary)
 
-   * add_help_ - Add a -h/--help option to the parser (default: ``True``)
+   * add_help_ - Add a ``-h/--help`` option to the parser (default: ``True``)
 
    * allow_abbrev_ - Allows long options to be abbreviated if the
      abbreviation is unambiguous. (default: ``True``)
@@ -211,7 +211,7 @@ The help for this program will display ``myprogram.py`` as the program name
     -h, --help  show this help message and exit
     --foo FOO   foo help
    $ cd ..
-   $ python subdir\myprogram.py --help
+   $ python subdir/myprogram.py --help
    usage: myprogram.py [-h] [--foo FOO]
 
    optional arguments:

Doc/library/unittest.rst

@@ -1637,11 +1637,11 @@ Loading and running tests
 
       The method optionally resolves *name* relative to the given *module*.
 
-   .. versionchanged:: 3.5
-      If an :exc:`ImportError` or :exc:`AttributeError` occurs while traversing
-      *name* then a synthetic test that raises that error when run will be
-      returned. These errors are included in the errors accumulated by
-      self.errors.
+      .. versionchanged:: 3.5
+         If an :exc:`ImportError` or :exc:`AttributeError` occurs while traversing
+         *name* then a synthetic test that raises that error when run will be
+         returned. These errors are included in the errors accumulated by
+         self.errors.
 
 
    .. method:: loadTestsFromNames(names, module=None)

Misc/NEWS

@@ -189,7 +189,7 @@ Library
   WeakValueDictionary.pop() when a GC collection happens in another
   thread.
 
-- Issue #20191: Fixed a crash in resource.prlimit() when pass a sequence that
+- Issue #20191: Fixed a crash in resource.prlimit() when passing a sequence that
   doesn't own its elements as limits.
 
 - Issue #28779: multiprocessing.set_forkserver_preload() would crash the

Modules/_collectionsmodule.c

@@ -2169,7 +2169,7 @@ static PyTypeObject defdict_type = {
 PyDoc_STRVAR(_count_elements_doc,
 "_count_elements(mapping, iterable) -> None\n\
 \n\
-Count elements in the iterable, updating the mappping");
+Count elements in the iterable, updating the mapping");
 
 static PyObject *
 _count_elements(PyObject *self, PyObject *args)

Modules/_io/textio.c

@@ -1012,7 +1012,7 @@ _io_TextIOWrapper___init___impl(textio *self, PyObject *buffer,
                                                            errors);
         if (self->encoder == NULL)
             goto error;
-        /* Get the normalized named of the codec */
+        /* Get the normalized name of the codec */
         res = _PyObject_GetAttrId(codec_info, &PyId_name);
         if (res == NULL) {
             if (PyErr_ExceptionMatches(PyExc_AttributeError))

Objects/odictobject.c

@@ -2237,7 +2237,7 @@ odictvalues_new(PyObject *od)
 
 
 /* ----------------------------------------------
-   MutableMappping implementations
+   MutableMapping implementations
 
 Mapping: