17. shades copy

copy function, list, set, dict have this function 
list 
dictionary 
collection 
example: 
S = { "name": "caona", 
   "Hobby": { "Paly": "Music"} 
   } 

S1 = S 
# assignment, then s s1 and the same data is shared. Another one of the modifications will be modified, since the common memory address and value 
s2 = s.copy () 
# shallow copy, copy only the first layer 
# copy a new data, then the first data layer and s is s2 two different data, a modification of the first layer, the first layer of the other does not change, if the modification of the second data layer, or the same data 
Import Copy 
S3 = copy.deepcopy (S) 
# deep copy. whichever modifying layer are two independent data, if it comes to clone full two separate data