title: HashSets and HashTables in Python
body: <p>Is there any <strong>HashSet</strong> implementation in Python? I know <strong>HashTable</strong> can be represented using dictionaries, but how do we represent <strong>HashSet</strong> implementation.</p>
  
  <p>I am NOT looking for a data structure with the same methods as <strong>HashSets</strong> but rather someone with  a CONSTANT lookup time, or the order of O(1);</p>
  
  <p>Also, I want to know if the lookup time in a Python <code>Dictionary</code> is constant aka O(1)</p>