'''The difference between shallow and deep copying is only relevant for
compound objects (objects that contain other objects, like lists or
class instances).

• A shallow copy constructs a new compound object and then (to the
  extent possible) inserts the same objects into it that the
  original contains.

• A deep copy constructs a new compound object and then, recursively,
  inserts copies into it of the objects found in the original.'''

淺復(fù)制和深復(fù)制之間的區(qū)別僅與
復(fù)合對(duì)象（包含其他對(duì)象的對(duì)象，例如列表或
類實(shí)例）。

-淺表副本會(huì)構(gòu)造一個(gè)新的復(fù)合對(duì)象，然后（到
在可能的范圍內(nèi)）插入相同的對(duì)象
原始包含。

-深層副本會(huì)構(gòu)造一個(gè)新的復(fù)合對(duì)象，然后遞歸地
將原始文檔中找到的對(duì)象的“副本”插入其中。