title: Printing values from a defaultdict
body: <p>I'm writing some code that looks like this:</p>
  
  <pre><code>def check_states(inventory):
      inventory_list = defaultdict(list)
      for i in inventory:
          inventory_list[i['store_site']].append(i)
  </code></pre>
  
  <p>This will give me a defaultdict with a key of the <code>store_site</code> and a list of all the inventory there, which is information that has data in it in a further dictionary like received date, transferred date, serial number, state, etc.  So it is a dictionary that maps to  multiple values inside of it. So what we have is <strong>dictionary of a list of dictionaries.</strong> I want to print some, but not all of those values. So to the end of the function above I add:</p>
  
  <pre><code>for store in inventory_list:
      print(store['serial_id'])
  </code></pre>
  
  <p>and I get</p>
  
  <pre><code>TypeError: string indices must be integers.
  </code></pre>
  
  <p>I also have tried using <code>items()</code>:</p>
  
  <pre><code>for store in inventory_list.items():
      print(store['serial_id'])
  </code></pre>
  
  <p>and I get</p>
  
  <pre><code>TypeError: tuple indices must be integers, not str.
  </code></pre>
  
  <p>Can anyone help show me my error? I looked for similar questions, but most of the dictionary questions are about printing a 1:1 value, not a 1:many value.</p>
  
  <pre><code>{'store5278': [{'abstract_state': 'GONE',
  'aud_last_updated_time': '2017-03-29T08:03:20Z',
  'bin_id': 9178,
  'disposed_at': '2017-03-29T08:03:20Z',
  'entity_type': 'parts',
  'external_serial_id': '',
  'id': 8336471,
  'is_fake_serial_id': False,
  'is_model_active': True,
  'is_part_active': True,
  'is_vending_bin': False,
  'joint_asset_id': '_part_8336471',
  'last_updated_time': '2017-03-29T08:03:20Z',
  'model': 'Z-CAT6-16M-OR-UTP-AA-L-BBB',
  'model_apn': 'OrangePatch16M',
  'model_description': 'CAT6 Copper Patch Cord 16m PVC ORANGE ',
  'model_id': 7285,
  'model_mpn': '',
  'po_number': '312949',
  'received_at': '2017-03-23T14:38:25Z',
  'room': 'PARTS',
  'serial_id': '002042869',
  'state': 'CONSUMED',
  'state_id': '10',
  'store': 'store5278',
  'tracking_id': '7097553',
  'transferred_at': '2017-03-29T08:03:20Z',
  'type_id': 27,
  'type_name': 'Cable',
  'unit_cost': 0.0,
  'vendor': 'Excel',
  'vendor_id': 135}]}
  </code></pre>