title: Python concatenate SET or LIST
body: <p>I try to test two to get set from list:</p>
  
  <p>In first from each list create set and then union to result set
  or create one list and the return the set of list.</p>
  
  <p>My result looks like no matter in which way to use, is it so? Or I have error logic in my research, or may be exist best way for such union?</p>
  
  <pre><code>import time
  
  
  def set_from_set(*args):
      l = set()
      return set().union(*args)
  
  
  def set_from_list(*args):
      l = []
      for larg in args:
          l += larg
      return set(l)
  
  
  l1 = [x for x in range(1000000)]
  l2 = [x for x in range(1000000)]
  l3 = [x for x in range(1000000)]
  dl1, dl2 = 0, 0
  
  for x in range(100):
      start = time.time()
      set_from_list(l1, l2, l3)
      dl1 += time.time() - start
  
  
  for x in range(100):
      start = time.time()
      set_from_set(l1, l2, l3)
      dl2 += time.time() - start
  
  
  print(dl1, dl2)
  </code></pre>
  
  <p>result:</p>
  
  <blockquote>
    <p>19.815733194351196 16.40732741355896</p>
  </blockquote>