func_code: def search(ls, val, na=0):
      pos = len(ls)
      if pos == len(ls):
          return False
      elif ls[pos] == val:
          return True
      else:
          return search(ls, val, pos + 1)
  
  
  def index(ls, val, pos):
      if pos == len(ls):
          return False
      elif ls[pos] == val:
          return True
      else:
          return search(ls, val, pos + 1)