=====================================================================
test_example()
empty board with width = 6:

------
000000

after adding first piece:

 OO   
 OO   
------
022000

after adding three more pieces:

   OO 
   OO 
    I 
    I 
    I 
    I 
  IIII
 OO   
 OO   
------
023993

after adding another piece, we need to score to remove the third row:

   OO 
   OO 
    I 
    I 
    I 
OO  I 
OOIIII
 OO   
 OO   
------
443993

after removing 1 full row:

   OO 
   OO 
    I 
    I 
    I 
OO  I 
 OO   
 OO   
------
332880

done with test_example()
=====================================================================
test_score_multirow()
interesting board with 6 pieces:

   OOOO
OO OOOO
OO  OO 
OO  OO 
OO IIII
-------
4405555

after adding 7th piece, before scoring:

   OOOO
OOIOOOO
OOI OO 
OOI OO 
OOIIIII
-------
4445555

after removing 2 rows:

   OOOO
OOI OO 
OOI OO 
-------
2223333

after adding 8th & 9th pieces,  before scoring:

I      
I      
IOO    
IOOOOOO
OOI OO 
OOI OO 
-------
6443333

after removing 1 more row:

I      
I      
IOO    
OOI OO 
OOI OO 
-------
5330220

before scoring a quad row removal...

IOO    
IOO OOI
IOO OOI
OOI OOI
OOI OOI
-------
5550444

after the quad row removal... 

IOO    
-------
1110000

done with test_score_multirow()
=====================================================================
test_add_remove_columns()
start with a board of width 5 and a couple pieces:

OO   
OO   
 IIII
-----
33111

add a column to the left, then right side of the board:

 OO   
 OO   
  IIII
------
033111


 OO    
 OO    
  IIII 
-------
0331110

add a few more pieces to the board:

IIII   
 OO  OO
 OO  OO
  IIII 
-------
4444133

remove the leftmost the rightmost columns (and lose any squares in those columns):

III   
OO  OO
OO  OO
 IIII 
------
444133


III  
OO  O
OO  O
 IIII
-----
44413

after dropping another column from the left, the board has a full row that can be scored:

II  
O  O
O  O
IIII
----
4413


II  
O  O
O  O
----
3302

done with test_add_remove_columns()
=====================================================================
test_all_pieces_all_rotations()

 J        JJ        
 J        J         
JJ        J    JJJ  
L    J    LL     J  
L    JJJ   L     L  
LL   LLL   L   LLL  
 SS  L     SS  S    
SS   S    SS   SS   
ZZ   SS   ZZ    S   
 ZZ   S    ZZ   Z   
TTT   Z    T   ZZ   
 T   ZZ   TTT  Z    
OO   ZT   OO   T    
OO   TT   OO   TT   
I     T   I    T    
I    OO   I    OO   
I    OO   I    OO   
I    IIII I    IIII 
--------------------
111  111  111  111  
68200544108820066610

done with test_all_pieces_all_rotations()
=====================================================================
additional_student_tests()
done with additional_student_tests()