Consistent periods at the end of docstrings

Doc/library/itertools.rst

@@ -803,11 +803,11 @@ which incur interpreter overhead.
  import random
 
  def take(n, iterable):
- "Return first n items of the iterable as a list"
+ "Return first n items of the iterable as a list."
  return list(islice(iterable, n))
 
  def prepend(value, iterable):
- "Prepend a single value in front of an iterable"
+ "Prepend a single value in front of an iterable."
  # prepend(1, [2, 3, 4]) --> 1 2 3 4
  return chain([value], iterable)
 
@@ -825,15 +825,15 @@ which incur interpreter overhead.
  return starmap(func, repeat(args, times))
 
  def flatten(list_of_lists):
- "Flatten one level of nesting"
+ "Flatten one level of nesting."
  return chain.from_iterable(list_of_lists)
 
  def ncycles(iterable, n):
- "Returns the sequence elements n times"
+ "Returns the sequence elements n times."
  return chain.from_iterable(repeat(tuple(iterable), n))
 
  def tail(n, iterable):
- "Return an iterator over the last n items"
+ "Return an iterator over the last n items."
  # tail(3, 'ABCDEFG') --> E F G
  return iter(collections.deque(iterable, maxlen=n))
 
@@ -848,15 +848,15 @@ which incur interpreter overhead.
  next(islice(iterator, n, n), None)
 
  def nth(iterable, n, default=None):
- "Returns the nth item or a default value"
+ "Returns the nth item or a default value."
  return next(islice(iterable, n, None), default)
 
  def quantify(iterable, pred=bool):
  "Given a predicate that returns True or False, count the True results."
  return sum(map(pred, iterable))
 
  def all_equal(iterable):
- "Returns True if all the elements are equal to each other"
+ "Returns True if all the elements are equal to each other."
  g = groupby(iterable)
  return next(g, True) and not next(g, False)
 
@@ -918,7 +918,7 @@ which incur interpreter overhead.
  pass
 
  def sliding_window(iterable, n):
- "Collect data into overlapping fixed-length chunks or blocks"
+ "Collect data into overlapping fixed-length chunks or blocks."
  # sliding_window('ABCDEFG', 4) --> ABCD BCDE CDEF DEFG
  it = iter(iterable)
  window = collections.deque(islice(it, n-1), maxlen=n)
@@ -927,7 +927,7 @@ which incur interpreter overhead.
  yield tuple(window)
 
  def grouper(iterable, n, *, incomplete='fill', fillvalue=None):
- "Collect data into non-overlapping fixed-length chunks or blocks"
+ "Collect data into non-overlapping fixed-length chunks or blocks."
  # grouper('ABCDEFG', 3, fillvalue='x') --> ABC DEF Gxx
  # grouper('ABCDEFG', 3, incomplete='strict') --> ABC DEF ValueError
  # grouper('ABCDEFG', 3, incomplete='ignore') --> ABC DEF
@@ -943,7 +943,8 @@ which incur interpreter overhead.
  raise ValueError('Expected fill, strict, or ignore')
 
  def roundrobin(*iterables):
- "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
+ "Visit input iterables in a cycle until each is exhausted."
+ # roundrobin('ABC', 'D', 'EF') --> A D E B F C
  # Recipe credited to George Sakkis
  num_active = len(iterables)
  nexts = cycle(iter(it).__next__ for it in iterables)
@@ -966,7 +967,7 @@ which incur interpreter overhead.
  return filterfalse(pred, t1), filter(pred, t2)
 
  def subslices(seq):
- "Return all contiguous non-empty subslices of a sequence"
+ "Return all contiguous non-empty subslices of a sequence."
  # subslices('ABCD') --> A AB ABC ABCD B BC BCD C CD D
  slices = starmap(slice, combinations(range(len(seq) + 1), 2))
  return map(operator.getitem, repeat(seq), slices)
@@ -1019,13 +1020,15 @@ which incur interpreter overhead.
  """
  it = iter(it)
  transition = []
+
  def true_iterator():
  for elem in it:
  if predicate(elem):
  yield elem
  else:
  transition.append(elem)
  return
+
  return true_iterator(), chain(transition, it)