title: Python iteration over non-sequence
body: <p>I have this piece of code which creates a note and adds to the notebook. When I run this I get a Iteration over non-sequence error.</p>
  
  <pre><code>import datetime
  class Note:
      def __init__(self, memo, tags):
          self.memo = memo
          self.tags = tags
          self.creation_date = datetime.date.today()
  
  def __str__(self):
      return 'Memo={0}, Tag={1}'.format(self.memo, self.tags)
  
  
  class NoteBook:
       def __init__(self):
          self.notes = []
  
       def add_note(self,memo,tags):
          self.notes.append(Note(memo,tags))
  
  if __name__ == "__main__":
      firstnote = Note('This is my first memo','example')
      print(firstnote)
      Notes = NoteBook()
      Notes.add_note('Added thru notes','example-1')
      Notes.add_note('Added thru notes','example-2')
      for note in Notes:
          print(note.memo)
  </code></pre>
  
  <p>Error:</p>
  
  <pre>C:\Python27\Basics\OOP\formytesting>python notebook.py  
  Memo=This is my first memo, Tag=example  
  Traceback (most recent call last):  
    File "notebook.py", line 27, in   
      for note in Notes:  
  TypeError: iteration over non-sequence</pre>