class_docstr: Set the remembers the order elements were added
class_docstr_tok: ["Set","the","remembers","the","order","elements","were","added"]
code: def union(self, s):
      check_deterministic(s)
      n = self.copy()
      for elem in s:
          if elem not in n:
              n.add(elem)
      return n
  
imports: import types
  import weakref
  from collections.abc import MutableSet
label_desc: Use image node_id 6 for calling the OrderedSet obj's underlying member method code with example usage: obj.union(s) and returns: n