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13.6.2.3 NodeList Objects

A `NodeList` represents a sequence of nodes. These objects are used in two ways in the DOM Core recommendation: the `Element` objects provides one as it's list of child nodes, and the `getElementsByTagName()` and `getElementsByTagNameNS()` methods of `Node` return objects with this interface to represent query results.

The DOM Level 2 recommendation defines one method and one attribute for these objects:

`item`(i)
  Return the i'th item from the sequence, if there is one, or `None`. The index i is not allowed to be less then zero or greater than or equal to the length of the sequence.

`length`
  The number of nodes in the sequence.

In addition, the Python DOM interface requires that some additional support is provided to allow `NodeList` objects to be used as Python sequences. All `NodeList` implementations must include support for `__len__()` and `__getitem__()`; this allows iteration over the `NodeList` in `for` statements and proper support for the `len()` built-in function.

If a DOM implementation supports modification of the document, the `NodeList` implementation must also support the `__setitem__()` and `__delitem__()` methods.