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52  'operator-summary': '\nOperator precedence\n*******************\n\nThe following table summarizes the operator precedences in Python,\nfrom lowest precedence (least binding) to highest precedence (most\nbinding). Operators in the same box have the same precedence.  Unless\nthe syntax is explicitly given, operators are binary.  Operators in\nthe same box group left to right (except for comparisons, including\ntests, which all have the same precedence and chain from left to right\n--- see section *Comparisons* --- and exponentiation, which groups\nfrom right to left).\n\n+-------------------------------------------------+---------------------------------------+\n| Operator                                        | Description                           |\n+=================================================+=======================================+\n| ``lambda``                                      | Lambda expression                     |\n+-------------------------------------------------+---------------------------------------+\n| ``if`` -- ``else``                              | Conditional expression                |\n+-------------------------------------------------+---------------------------------------+\n| ``or``                                          | Boolean OR                            |\n+-------------------------------------------------+---------------------------------------+\n| ``and``                                         | Boolean AND                           |\n+-------------------------------------------------+---------------------------------------+\n| ``not`` ``x``                                   | Boolean NOT                           |\n+-------------------------------------------------+---------------------------------------+\n| ``in``, ``not in``, ``is``, ``is not``, ``<``,  | Comparisons, including membership     |\n| ``<=``, ``>``, ``>=``, ``<>``, ``!=``, ``==``   | tests and identity tests              |\n+-------------------------------------------------+---------------------------------------+\n| ``|``                                           | Bitwise OR                            |\n+-------------------------------------------------+---------------------------------------+\n| ``^``                                           | Bitwise XOR                           |\n+-------------------------------------------------+---------------------------------------+\n| ``&``                                           | Bitwise AND                           |\n+-------------------------------------------------+---------------------------------------+\n| ``<<``, ``>>``                                  | Shifts                                |\n+-------------------------------------------------+---------------------------------------+\n| ``+``, ``-``                                    | Addition and subtraction              |\n+-------------------------------------------------+---------------------------------------+\n| ``*``, ``/``, ``//``, ``%``                     | Multiplication, division, remainder   |\n|                                                 | [8]                                   |\n+-------------------------------------------------+---------------------------------------+\n| ``+x``, ``-x``, ``~x``                          | Positive, negative, bitwise NOT       |\n+-------------------------------------------------+---------------------------------------+\n| ``**``                                          | Exponentiation [9]                    |\n+-------------------------------------------------+---------------------------------------+\n| ``x[index]``, ``x[index:index]``,               | Subscription, slicing, call,          |\n| ``x(arguments...)``, ``x.attribute``            | attribute reference                   |\n+-------------------------------------------------+---------------------------------------+\n| ``(expressions...)``, ``[expressions...]``,     | Binding or tuple display, list        |\n| ``{key: value...}``, ```expressions...```       | display, dictionary display, string   |\n|                                                 | conversion                            |\n+-------------------------------------------------+---------------------------------------+\n\n-[ Footnotes ]-\n\n[1] In Python 2.3 and later releases, a list comprehension "leaks" the\n    control variables of each ``for`` it contains into the containing\n    scope.  However, this behavior is deprecated, and relying on it\n    will not work in Python 3.\n\n[2] While ``abs(x%y) < abs(y)`` is true mathematically, for floats it\n    may not be true numerically due to roundoff.  For example, and\n    assuming a platform on which a Python float is an IEEE 754 double-\n    precision number, in order that ``-1e-100 % 1e100`` have the same\n    sign as ``1e100``, the computed result is ``-1e-100 + 1e100``,\n    which is numerically exactly equal to ``1e100``.  The function\n    ``math.fmod()`` returns a result whose sign matches the sign of\n    the first argument instead, and so returns ``-1e-100`` in this\n    case. Which approach is more appropriate depends on the\n    application.\n\n[3] If x is very close to an exact integer multiple of y, it\'s\n    possible for ``floor(x/y)`` to be one larger than ``(x-x%y)/y``\n    due to rounding.  In such cases, Python returns the latter result,\n    in order to preserve that ``divmod(x,y)[0] * y + x % y`` be very\n    close to ``x``.\n\n[4] While comparisons between unicode strings make sense at the byte\n    level, they may be counter-intuitive to users. For example, the\n    strings ``u"\\u00C7"`` and ``u"\\u0043\\u0327"`` compare differently,\n    even though they both represent the same unicode character (LATIN\n    CAPITAL LETTER C WITH CEDILLA). To compare strings in a human\n    recognizable way, compare using ``unicodedata.normalize()``.\n\n[5] The implementation computes this efficiently, without constructing\n    lists or sorting.\n\n[6] Earlier versions of Python used lexicographic comparison of the\n    sorted (key, value) lists, but this was very expensive for the\n    common case of comparing for equality.  An even earlier version of\n    Python compared dictionaries by identity only, but this caused\n    surprises because people expected to be able to test a dictionary\n    for emptiness by comparing it to ``{}``.\n\n[7] Due to automatic garbage-collection, free lists, and the dynamic\n    nature of descriptors, you may notice seemingly unusual behaviour\n    in certain uses of the ``is`` operator, like those involving\n    comparisons between instance methods, or constants.  Check their\n    documentation for more info.\n\n[8] The ``%`` operator is also used for string formatting; the same\n    precedence applies.\n\n[9] The power operator ``**`` binds less tightly than an arithmetic or\n    bitwise unary operator on its right, that is, ``2**-1`` is\n    ``0.5``.\n',
67 ost of the attributes labelled "Writable" check the type of the\n assigned value.\n\n Changed in version 2.4: ``func_name`` is now writable.\n\n Function objects also support getting and setting arbitrary\n attributes, which can be used, for example, to attach metadata\n to functions. Regular attribute dot-notation is used to get and\n set such attributes. *Note that the current implementation only\n supports function attributes on user-defined functions. Function\n attributes on built-in functions may be supported in the\n future.*\n\n Additional information about a function\'s definition can be\n retrieved from its code object; see the description of internal\n types below.\n\n User-defined methods\n A user-defined method object combines a class, a class instance\n (or ``None``) and any callable object (normally a user-defined\n function).\n\n Special read-only attributes: ``im_self`` is the class instance\n object, ``im_func`` is the function object; ``im_class`` is the\n class of ``im_self`` for bound methods or the class that asked\n for the method for unbound methods; ``__doc__`` is the method\'s\n documentation (same as ``im_func.__doc__``); ``__name__`` is the\n method name (same as ``im_func.__name__``); ``__module__`` is\n the name of the module the method was defined in, or ``None`` if\n unavailable.\n\n Changed in version 2.2: ``im_self`` used to refer to the class\n that defined the method.\n\n Changed in version 2.6: For Python 3 forward-compatibility,\n ``im_func`` is also available as ``__func__``, and ``im_self``\n as ``__self__``.\n\n Methods also support accessing (but not setting) the arbitrary\n function attributes on the underlying function object.\n\n User-defined method objects may be created when getting an\n attribute of a class (perhaps via an instance of that class), if\n that attribute is a user-defined function object, an unbound\n user-defined method object, or a class method object. When the\n attribute is a user-defined method object, a new method object\n is only created if the class from which it is being retrieved is\n the same as, or a derived class of, the class stored in the\n original method object; otherwise, the original method object is\n used as it is.\n\n When a user-defined method object is created by retrieving a\n user-defined function object from a class, its ``im_self``\n attribute is ``None`` and the method object is said to be\n unbound. When one is created by retrieving a user-defined\n function object from a class via one of its instances, its\n ``im_self`` attribute is the instance, and the method object is\n said to be bound. In either case, the new method\'s ``im_class``\n attribute is the class from which the retrieval takes place, and\n its ``im_func`` attribute is the original function object.\n\n When a user-defined method object is created by retrieving\n another method object from a class or instance, the behaviour is\n the same as for a function object, except that the ``im_func``\n attribute of the new instance is not the original method object\n but its ``im_func`` attribute.\n\n When a user-defined method object is created by retrieving a\n class method object from a class or instance, its ``im_self``\n attribute is the class itself, and its ``im_func`` attribute is\n the function object underlying the class method.\n\n When an unbound user-defined method object is called, the\n underlying function (``im_func``) is called, with the\n restriction that the first argument must be an instance of the\n proper class (``im_class``) or of a derived class thereof.\n\n When a bound user-defined method object is called, the\n underlying function (``im_func``) is called, inserting the class\n instance (``im_self``) in front of the argument list. For\n instance, when ``C`` is a class which contains a definition for\n a function ``f()``, and ``x`` is an instance of ``C``, calling\n ``x.f(1)`` is equivalent to calling ``C.f(x, 1)``.\n\n When a user-defined method object is derived from a class method\n object, the "class instance" stored in ``im_self`` will actually\n be the class itself, so that calling either ``x.f(1)`` or\n ``C.f(1)`` is equivalent to calling ``f(C,1)`` where ``f`` is\n the underlying function.\n\n Note that the transformation from function object to (unbound or\n bound) method object happens each time the attribute is\n retrieved from the class or instance. In some cases, a fruitful\n optimization is to assign the attribute to a local variable and\n call that local variable. Also notice ``stop`` is the upper bound; ``step`` is the step value; each is\n ``None`` if omitted. These attributes can have any type.\n\n Slice objects support one method:\n\n slice.indices(self, length)\n\n This method takes a single integer argument *length* and\n computes information about the extended slice that the slice\n object would describe if applied to a sequence of *length*\n items. It returns a tuple of three integers; respectively\n these are the *start* and *stop* indices and the *step* or\n stride length of the slice. Missing or out-of-bounds indices\n are handled in a manner consistent with regular slices.\n\n New in version 2.3.\n\n Static method objects\n Static method objects provide a way of defeating the\n transformation of function objects to method objects described\n above. A static method object is a wrapper around any other\n object, usually a user-defined method object. When a static\n method object is retrieved from a class or a class instance, the\n object actually returned is the wrapped object, which is not\n subject to any further transformation. Static method objects are\n not themselves callable, although the objects they wrap usually\n are. Static method objects are created by the built-in\n ``staticmethod()`` constructor.\n\n Class method objects\n A class method object, like a static method object, is a wrapper\n around another object that alters the way in which that object\n is retrieved from classes and class instances. The behaviour of\n class method objects upon such retrieval is described above,\n under "User-defined methods". Class method objects are created\n by the built-in ``classmethod()`` constructor.\n',