title: issue with Storing dictionary with key and multi values for key in python
body: <p>I have a loop on utterances(list of statements)</p>
  
  <pre><code>predicted_utt_label=defaultdict(list)
  for utt in test_utterances:
           #here some code to detect label for each statement
  </code></pre>
  
  <p>Now I want to add utterance and its label in a dictionary and write the code here:</p>
  
  <pre><code> predicted_utt_label[utt]=DA
  </code></pre>
  
  <p>But there is a problem with the statement like 'I don't know' and 'I don't know' with different labels like 'sd' and 'qy'. As both statements have different labels then how I can store them as statement key of dictionary and labels as multi value of that key? Because dictionary always have unique keys.</p>