input: 
  def print_chessboard():
      """Prints a 7x7 chessboard pattern using '#' and spaces.
      >>> print_chessboard()
      # # # # #
       # # # # #
      # # # # #
       # # # # #
      # # # # #
       # # # # #
      # # # # #
      """
      for i in range(7):
          for j in range(7):
              if (i + j) % 2 == 0:
                  print('#', end='')
              else:
                  print(' ', end='')
          print()
  
output:     for i in range(7):
          for j in range(7):
              if (i + j) % 2 == 0:
                  print('#', end='')
              else:
                  print(' ', end='')
          print()