   end
 
   @doc """
-  Returns a set containing only members in common between the two input sets.
+  Returns a set containing only members in common between `set1` and `set2`.
 
   ## Examples
 
       iex> Set.intersection(HashSet.new([1,2]), HashSet.new([2,3,4])) |> HashSet.to_list
       [2]
+
+      iex> Set.intersection(HashSet.new([1,2]), HashSet.new([3,4])) |> HashSet.to_list  
+      []
 
   """
   @spec intersection(t, t) :: t

  end

  @doc """
  Puts the given value into the set if it does not already contain it.

  ## Examples


  end

  @doc """
  Returns a set containing all members of `set1` and `set2`.

  ## Examples

