Minor named tuple clean-ups.

Doc/library/collections.rst

@@ -711,7 +711,7 @@ they add the ability to access fields by name instead of position index.
    >>> p = Point(x=10, y=11)
 
    >>> # Example using the verbose option to print the class definition
-   >>> Point = namedtuple('Point', 'x y', verbose=True)
+   >>> Point = namedtuple('Point', ['x', 'y'], verbose=True)
    class Point(tuple):
        'Point(x, y)'
    <BLANKLINE>
@@ -743,7 +743,7 @@ they add the ability to access fields by name instead of position index.
            'Return a new Point object replacing specified fields with new values'
            result = _self._make(map(kwds.pop, ('x', 'y'), _self))
            if kwds:
-                   raise ValueError('Got unexpected field names: %r' % list(kwds.keys()))
+               raise ValueError('Got unexpected field names: %r' % list(kwds))
            return result
    <BLANKLINE>
        def __getnewargs__(self):
@@ -751,6 +751,7 @@ they add the ability to access fields by name instead of position index.
            return tuple(self)
    <BLANKLINE>
        x = _property(_itemgetter(0), doc='Alias for field number 0')
+   <BLANKLINE>
        y = _property(_itemgetter(1), doc='Alias for field number 1')
 
    >>> p = Point(11, y=22)     # instantiate with positional or keyword arguments
@@ -867,7 +868,6 @@ a fixed-width print format:
 The subclass shown above sets ``__slots__`` to an empty tuple.  This helps
 keep memory requirements low by preventing the creation of instance dictionaries.
 
-
 Subclassing is not useful for adding new, stored fields.  Instead, simply
 create a new named tuple type from the :attr:`_fields` attribute:
 
@@ -879,6 +879,7 @@ customize a prototype instance:
     >>> Account = namedtuple('Account', 'owner balance transaction_count')
     >>> default_account = Account('<owner name>', 0.0, 0)
     >>> johns_account = default_account._replace(owner='John')
+    >>> janes_account = default_account._replace(owner='Jane')
 
 Enumerated constants can be implemented with named tuples, but it is simpler
 and more efficient to use a simple class declaration:

Lib/collections/__init__.py

@@ -265,7 +265,7 @@ class {typename}(tuple):
         'Return a new {typename} object replacing specified fields with new values'
         result = _self._make(map(kwds.pop, {field_names!r}, _self))
         if kwds:
-            raise ValueError('Got unexpected field names: %r' % kwds.keys())
+            raise ValueError('Got unexpected field names: %r' % list(kwds))
         return result
 
     def __getnewargs__(self):
@@ -309,18 +309,17 @@ def namedtuple(typename, field_names, verbose=False, rename=False):
     # generating informative error messages and preventing template injection attacks.
     if isinstance(field_names, str):
         field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas
-    field_names = tuple(map(str, field_names))
+    field_names = list(map(str, field_names))
     if rename:
-        names = list(field_names)
         seen = set()
-        for i, name in enumerate(names):
-            if (not all(c.isalnum() or c=='_' for c in name) or _iskeyword(name)
+        for index, name in enumerate(field_names):
+            if (not all(c.isalnum() or c=='_' for c in name)
+                or _iskeyword(name)
                 or not name or name[0].isdigit() or name.startswith('_')
                 or name in seen):
-                names[i] = '_%d' % i
+                field_names[index] = '_%d' % index
             seen.add(name)
-        field_names = tuple(names)
-    for name in (typename,) + field_names:
+    for name in [typename] + field_names:
         if not all(c.isalnum() or c=='_' for c in name):
             raise ValueError('Type names and field names can only contain alphanumeric characters and underscores: %r' % name)
         if _iskeyword(name):
@@ -338,9 +337,9 @@ def namedtuple(typename, field_names, verbose=False, rename=False):
     # Fill-in the class template
     class_definition = _class_template.format(
         typename = typename,
-        field_names = field_names,
+        field_names = tuple(field_names),
         num_fields = len(field_names),
-        arg_list = repr(field_names).replace("'", "")[1:-1],
+        arg_list = repr(tuple(field_names)).replace("'", "")[1:-1],
         repr_fmt = ', '.join(_repr_template.format(name=name) for name in field_names),
         field_defs = '\n'.join(_field_template.format(index=index, name=name)
                                for index, name in enumerate(field_names))