title: Python frozenset writing to JSON
body: <p>I have a dictionary with frozenset-typed (variable-length, non-duplicate data) keys and I need to write this dictionary into a JSON file.</p>
  
  <p>However, my problem is that frozenset (although immutable) is not a Python simple data type and I get this type error in result of <code>json.dump(myDict, myFile)</code>:</p>
  
  <blockquote>
    <p>TypeError: key frozenset({'myKey'}) is not a string</p>
  </blockquote>
  
  <p>Could anyone please help me with some hints or solutions? I'm using Python 3.4.</p>
  
  <p>I know I can manually serialize the object, but aren't there any other more automatic ways?!</p>