title: Scala: What does mean to pass a Set to the map function of a set
body: <p>I've just seen I can do:</p>
  
  <pre><code>Set(1, 2, 3).map(Set(1))
  </code></pre>
  
  <p>which yields the result:</p>
  
  <pre><code>Set(true, false)
  </code></pre>
  
  <p>But I thought that the map function can only take another function not a new Set. If anything I'd expect this to return a set of sets. What's going on and what does the result mean?</p>