Peekable iterator wrapper in Python3

peekable.py

class Peekable():
  """An iterable class which can return the next element of the wrapped
  iterator without advancing it."""
  def __init__(self, iterator):
     self.iterator = iterator
     self.peeked = False
  
  def peek(self):
     if not self.peeked:
       self.peeked = True
       self.head = next(iterator)
       return self.head
 
  def __next__(self):
    if self.peeked:
      self.peeked = False
      return self.head
    else:
      return next(iterator)

class Peekable(object):
    """An iterable class which can return the next element of the wrapped
    iterator without advancing it."""

    def __init__(self, iterator):
        self.head = None
        self.iterator = iterator
        self.peeked = False

    def peek(self):
        if not self.peeked:
            self.peeked = True
            self.head = next(self.iterator)
            return self.head

    def __next__(self):
        if self.peeked:
            self.peeked = False
            return self.head
        else:
            return next(self.iterator)