Single

First

red        green
     blue       
red        green


Second

      blue       
red?        green
      blue       


Nested

red        green.       blue               blue        
     blue          red        green   red        green 
red        green        blue               blue        
                                                       
     blue.         red        green        blue        
red         green       blue          red        green 
     blue          red        green!       blue        
                                                       
red        green        blue               blue        
     blue          red        green   red         green
red        green        blue               blue!