diff --git a/Lib/collections.py b/Lib/collections.py
index 4a860dd..c2b1176 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -8,33 +8,42 @@
     """Returns a new subclass of tuple with named fields.
 
     >>> Point = NamedTuple('Point', 'x y')
-    >>> Point.__doc__           # docstring for the new class
+    >>> Point.__doc__                   # docstring for the new class
     'Point(x, y)'
-    >>> p = Point(11, y=22)     # instantiate with positional args or keywords
-    >>> p[0] + p[1]             # works just like the tuple (11, 22)
+    >>> p = Point(11, y=22)             # instantiate with positional args or keywords
+    >>> p[0] + p[1]                     # works just like the tuple (11, 22)
     33
-    >>> x, y = p                # unpacks just like a tuple
+    >>> x, y = p                        # unpacks just like a tuple
     >>> x, y
     (11, 22)
-    >>> p.x + p.y               # fields also accessable by name
+    >>> p.x + p.y                       # fields also accessable by name
     33
-    >>> p                       # readable __repr__ with name=value style
+    >>> p                               # readable __repr__ with name=value style
     Point(x=11, y=22)
+    >>> p.__replace__('x', 100)         # __replace__() is like str.replace() but targets a named field
+    Point(x=100, y=22)
+    >>> d = dict(zip(p.__fields__, p))  # use __fields__ to make a dictionary
+    >>> d['x']
+    11
 
     """
 
-    field_names = s.split()
-    if not ''.join([typename] + field_names).replace('_', '').isalnum():
+    field_names = tuple(s.replace(',', ' ').split())   # names separated by spaces and/or commas
+    if not ''.join((typename,) + field_names).replace('_', '').isalnum():
         raise ValueError('Type names and field names can only contain alphanumeric characters and underscores')
     argtxt = ', '.join(field_names)
     reprtxt = ', '.join('%s=%%r' % name for name in field_names)
     template = '''class %(typename)s(tuple):
         '%(typename)s(%(argtxt)s)'
         __slots__ = ()
+        __fields__ = %(field_names)r
         def __new__(cls, %(argtxt)s):
             return tuple.__new__(cls, (%(argtxt)s,))
         def __repr__(self):
             return '%(typename)s(%(reprtxt)s)' %% self
+        def __replace__(self, field, value):
+            'Return a new %(typename)s object replacing one field with a new value'
+            return %(typename)s(**dict(zip(%(field_names)r, self) + [(field, value)]))
     ''' % locals()
     for i, name in enumerate(field_names):
         template += '\n        %s = property(itemgetter(%d))\n' % (name, i)
@@ -51,9 +60,9 @@
 
 
 if __name__ == '__main__':
-    # verify that instances are pickable
+    # verify that instances can be pickled
     from cPickle import loads, dumps
-    Point = NamedTuple('Point', 'x y')
+    Point = NamedTuple('Point', 'x, y')
     p = Point(x=10, y=20)
     assert p == loads(dumps(p))