input: 
  def print_pattern():
      """Prints a pattern of 7x7 grid where each cell is either '#' or ' '. 
      Cells with (row + column) % 2 == 0 are filled with '#'.
      
      >>> print_pattern()
      ## 
      # # 
      ##  
      # # 
      ##  
      # # 
      ##  
      """
  
output:     for row in range(7):
          for col in range(7):
              if (row + col) % 2 == 0:
                  print('#', end='')
              else:
                  print(' ', end='')
          print()