input: 
  def print_grid():
      """ Given a task, print a grid with '#' at coordinates (i, j) where (i + j) % 2 == 0,
      and ' ' otherwise. The grid should be 7x7 in size.
      >>> print_grid()
      # # # # #
       # # # # 
      # # # # #
       # # # # 
      # # # # #
       # # # # 
      # # # # #
      """
      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()