Parsing XML documentation has a gotcha for noobies...

[xtian]

As a Python Noob, I hesitate to mention this; however, there seems to be a strange gotcha in the [documentation](http://lxml.de/parsing.html#parsers) which can quickly be remedied.

Learning the parsing operations I was simply copying and pasting these instructions,
[code]
>>> from lxml import etree
[...]
>>> xml = '<a xmlns="test"><b xmlns="test"/></a>'
>>> root = etree.fromstring(xml)
>>> etree.tostring(root)
b'<a xmlns="test"><b xmlns="test"/></a>'
[...]
>>> tree = etree.parse(StringIO(xml))
>>> etree.tostring(tree.getroot())
b'<a xmlns="test"><b xmlns="test"/></a>'
[/code]

first I got the error,
    At NameError: name 'StringIO' is not defined

I recognized the StringIO module likely needed to be imported. But the fix
    >>> from StringIO import StringIO

is not described in the documentation and involves a gotcha a Noob may not expect and other Python programmers admit is [strange] (https://mail.python.org/pipermail/python-ideas/2009-February/003081.html).

----
>>> print("%-20s: %s" % ('lxml.etree', etree.LXML_VERSION))
lxml.etree : (3, 3, 0, -95)
>>> print("%-20s: %s" % ('libxml used', etree.LIBXML_VERSION))
libxml used : (2, 9, 1)
>>> print("%-20s: %s" % ('libxml compiled', etree.LIBXML_COMPILED_VERSION))
libxml compiled : (2, 9, 1)
>>> print("%-20s: %s" % ('libxslt used', etree.LIBXSLT_VERSION))
libxslt used : (1, 1, 28)
>>> print("%-20s: %s" % ('libxslt compiled', etree.LIBXSLT_COMPILED_VERSION))
libxslt compiled : (1, 1, 28)
---

[scoder (scoder)]

StringIO is a bit tricky because it was moved around in Py3. But it's generally available as "io.StringIO" these days. I added that to the docs. Thanks for the suggestion.

[scoder (scoder)]

Docs updated in lxml 3.3.2.