title: Getting an error 'unhashable type list' in python when working with a file and dictionaries
body: <p>for an assignment, I'm trying to to create a python dictionary. The dictionary's keys are a set of email addresses, which are stored in a list and the values are the amount of times each address appears in the list. Here is the code I'm using to create this dictionary. The object I'm iterating <code>addresses</code> is the list containing the email addresses. The error I get is 'unhashable type: list'. Any help would be useful. </p>
  
  <pre><code>count = {}
  for j in addresses:
      count[addresses] = count.get(addresses, 0) + 1
  </code></pre>