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| Built-in Constants |
| ================== |
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| A small number of constants live in the built-in namespace. They are: |
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| .. XXX False, True, None are keywords too |
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| .. data:: False |
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| The false value of the :class:`bool` type. |
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| .. data:: True |
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| The true value of the :class:`bool` type. |
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| .. data:: None |
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| The sole value of :attr:`types.NoneType`. ``None`` is frequently used to |
| represent the absence of a value, as when default arguments are not passed to a |
| function. |
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| .. data:: NotImplemented |
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| Special value which can be returned by the "rich comparison" special methods |
| (:meth:`__eq__`, :meth:`__lt__`, and friends), to indicate that the comparison |
| is not implemented with respect to the other type. |
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| .. data:: Ellipsis |
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| The same as ``...``. Special value used mostly in conjunction with extended |
| slicing syntax for user-defined container data types, as in :: |
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| val = container[1:5, 7:10, ...] |