- #https://i...content-available-to-author-only...e.com/XKyhyR 
-   
- n = 42;  
- #rev = 0 
- new= [] 
- m = 0 
-   
- def convert(n,m): 
-     print "round #:", m,"n :", n 
-     a = ((n+1) % 3)-1 
-     if n: 
-         new.append(a); print 'new :', new 
-         print 'call convert(', (n+1)//3,',',m+1,'):', convert((n+1)//3,m+1) 
-         print 'after convert(' , n, ',' ,m,  ')','\n' 
-     else: 
-         print 'n==',n, 'new: ::: ', new,'\n\n', 
-         return new, n 
-   
- print  convert(n,m), "<<---- None returned ? " 
-   
- sum = 0 
-   
- def value(l): 
-     sum = 0 
-     for i in range(0, len(new),1): 
-         sum += new[i]*(3**i) 
-         print "sum :" , sum 
-     return sum 
-   
- #print value(new),  
				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
				
				
				
				
				
			 
			
				
			
			
				
	
		
		
	
	
		round #: 0 n : 42
new : [0]
call convert( 14 , 1 ): round #: 1 n : 14
new : [0, -1]
call convert( 5 , 2 ): round #: 2 n : 5
new : [0, -1, -1]
call convert( 2 , 3 ): round #: 3 n : 2
new : [0, -1, -1, -1]
call convert( 1 , 4 ): round #: 4 n : 1
new : [0, -1, -1, -1, 1]
call convert( 0 , 5 ): round #: 5 n : 0
n== 0 new: :::  [0, -1, -1, -1, 1] 
([0, -1, -1, -1, 1], 0)
after convert( 1 , 4 ) 
None
after convert( 2 , 3 ) 
None
after convert( 5 , 2 ) 
None
after convert( 14 , 1 ) 
None
after convert( 42 , 0 ) 
None <<---- None returned ?