input: 
  def print_chessboard(size: int) -> None:
      """ Print a chessboard pattern of given size. 
      >>> print_chessboard(7)
      # # # # # # # 
      # # # # # # # 
      # # # # # # # 
       # # # # # # # 
      # # # # # # # 
      # # # # # # # 
      # # # # # # #
      """
  
output:     for i in range(size):
          if i % 2 == 0:
              print("# " * (size // 2) + "#" * (size % 2))
          else:
              print(" #" * (size // 2) + " " * (size % 2))