func_code: def union(f1con, f2con):
      union = []
      i = 0
      while i != len(f1con):
          union.append(f1con[i])
          i = i + 1
      i = 0
      while i != len(f2con):
          union.append(f2con[i])
          i = i + 1
      union = sorted(list(set(union)))
      return union