A= 
[[0,1,2]
 [10,11,12]]
 D= 
[[0,0.1,0.2]
 [1,1.1,1.2]]
 C= [(0,0),(1,1),(2,2),(3,3),(4,4)]
 Arange(0,1),range(1,3)  = 
[[1,2]
 [11,12]]
B = 
[[0,1,2]
 [10,11,12]]
Bf = 
[[0,1,2]
 [10,11,12]]
D = 
[[0,0.1,0.2]
 [1,1.1,1.2]]
C = [(0,0),(1,1),(2,2),(3,3),(4,4)]
(xx) ---> 2.3
(s2) ---> a nice chain