input: def print_chessboard_pattern():
      """Prints a 7x7 chessboard pattern where '#' represents a black square and ' ' represents a white square.
      The pattern is determined by (i + j) % 2 == 0, where i and j are the row and column indices respectively.
      >>> print_chessboard_pattern()
      # # # # 
       # # # #
      # # # # 
       # # # #
      # # # # 
       # # # #
      # # # # 
      """
      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()