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+
+:mod:`copy` --- Shallow and deep copy operations
+================================================
+
+.. module:: copy
+   :synopsis: Shallow and deep copy operations.
+
+
+.. index::
+   single: copy() (in copy)
+   single: deepcopy() (in copy)
+
+This module provides generic (shallow and deep) copying operations.
+
+Interface summary::
+
+   import copy
+
+   x = copy.copy(y)        # make a shallow copy of y
+   x = copy.deepcopy(y)    # make a deep copy of y
+
+For module specific errors, :exc:`copy.error` is raised.
+
+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 *references* into it to the objects found in the original.
+
+* A *deep copy* constructs a new compound object and then, recursively, inserts
+  *copies* into it of the objects found in the original.
+
+Two problems often exist with deep copy operations that don't exist with shallow
+copy operations:
+
+* Recursive objects (compound objects that, directly or indirectly, contain a
+  reference to themselves) may cause a recursive loop.
+
+* Because deep copy copies *everything* it may copy too much, e.g.,
+  administrative data structures that should be shared even between copies.
+
+The :func:`deepcopy` function avoids these problems by:
+
+* keeping a "memo" dictionary of objects already copied during the current
+  copying pass; and
+
+* letting user-defined classes override the copying operation or the set of
+  components copied.
+
+This module does not copy types like module, method, stack trace, stack frame,
+file, socket, window, array, or any similar types.  It does "copy" functions and
+classes (shallow and deeply), by returning the original object unchanged; this
+is compatible with the way these are treated by the :mod:`pickle` module.
+
+Shallow copies of dictionaries can be made using :meth:`dict.copy`, and
+of lists by assigning a slice of the entire list, for example,
+``copied_list = original_list[:]``.
+
+.. versionchanged:: 2.5
+   Added copying functions.
+
+.. index:: module: pickle
+
+Classes can use the same interfaces to control copying that they use to control
+pickling.  See the description of module :mod:`pickle` for information on these
+methods.  The :mod:`copy` module does not use the :mod:`copy_reg` registration
+module.
+
+.. index::
+   single: __copy__() (copy protocol)
+   single: __deepcopy__() (copy protocol)
+
+In order for a class to define its own copy implementation, it can define
+special methods :meth:`__copy__` and :meth:`__deepcopy__`.  The former is called
+to implement the shallow copy operation; no additional arguments are passed.
+The latter is called to implement the deep copy operation; it is passed one
+argument, the memo dictionary.  If the :meth:`__deepcopy__` implementation needs
+to make a deep copy of a component, it should call the :func:`deepcopy` function
+with the component as first argument and the memo dictionary as second argument.
+
+
+.. seealso::
+
+   Module :mod:`pickle`
+      Discussion of the special methods used to support object state retrieval and
+      restoration.
+