title: How to find all frozensets that are subsets of another frozenset in a set of frozensets?
body: <p>I am having trouble searching for the solution (if previously asked) to this problem because it's kind of hard to explain in a search.</p>
  
  <p>I have a set of frozensets, like:</p>
  
  <pre><code>my_set = {
      frozenset({1, 2, 3}),
      frozenset({1, 2, 3, 4}),
      frozenset({1, 2, 3, 5}),
      frozenset({1, 3, 5}),
      frozenset({1, 2})
  }
  </code></pre>
  
  <p>I want all the frozensets that are subsets of any other frozenset in the set, with a function <code>get_subsets</code> whose output is like:</p>
  
  <pre><code>subsets = get_subsets(my_set)
  subsets == {
      frozenset({1, 2, 3}),
      frozenset({1, 3, 5}),
      frozenset({1, 2})
  }
  </code></pre>
  
  <p>would return True. How can I get this? I previously had a set of tuples but revised to frozensets, as I was using touples before because they are hashable. I also asked to do it without iterating over the set because in my case I have hundreds of thousands of items in my set; now I revise to:</p>
  
  <p>What's the fastest way to do this (now embracing iteration)?</p>