Dictionary update method

Usage: dict . Update ( dict2 )
 dict change immediately! The return value is None 


A = { 'A':. 1, 'B': 2, 'C':. 3} 
B = { 'D':. 4, 'E':. 5} 
a.update (B) 
Print (A) 
the return value update process is None, a immediately changed 
>>> { 'a':. 1, 'B': 2, 'C':. 3, 'D':. 4, 'E':. 5}

 a = { ' A ':. 1,' B ': 2,' C ':. 3} 
B = {' A ':. 4,' E ':. 5} 

a.update (B) 
Print (A) 
>>> {' A ': 4, 'b': 2, 'c': 3, 'e': 5}