128 def deepcopy(x, memo=None, _nil=[]):  argument
134     if memo is None:
135         memo = {}
138     y = memo.get(d, _nil)
146         y = copier(x, memo)
149             y = _deepcopy_atomic(x, memo)
153                 y = copier(memo)
172                     y = _reconstruct(x, memo, *rv)
176         memo[d] = y
177         _keep_alive(x, memo) # Make sure x lives at least as long as d
182 def _deepcopy_atomic(x, memo):  argument
201 def _deepcopy_list(x, memo, deepcopy=deepcopy):  argument
203     memo[id(x)] = y
206         append(deepcopy(a, memo))
210 def _deepcopy_tuple(x, memo, deepcopy=deepcopy):  argument
211     y = [deepcopy(a, memo) for a in x]
215         return memo[id(x)]
227 def _deepcopy_dict(x, memo, deepcopy=deepcopy):  argument
229     memo[id(x)] = y
231         y[deepcopy(key, memo)] = deepcopy(value, memo)
237 def _deepcopy_method(x, memo): # Copy instance methods  argument
238     return type(x)(x.__func__, deepcopy(x.__self__, memo))
243 def _keep_alive(x, memo):  argument
254         memo[id(memo)].append(x)
257         memo[id(memo)]=[x]
259 def _reconstruct(x, memo, func, args,  argument
262     deep = memo is not None
264         args = (deepcopy(arg, memo) for arg in args)
267         memo[id(x)] = y
271             state = deepcopy(state, memo)
288                 item = deepcopy(item, memo)
296                 key = deepcopy(key, memo)
297                 value = deepcopy(value, memo)