lxml ignore none in getchildren

[Sayth Renshaw]

I am following John Shipmans example from http://infohost.nmt.edu/~shipman/soft/pylxml/web/Element-getchildren.html

>>> xml = '''<corral><horse n="2"/><cow n="17"/>
...  <cowboy n="2"/></corral>'''
>>> pen = etree.fromstring(xml)
>>> penContents = pen.getchildren()
>>> for  content in penContents:
...     print "%-10s %3s" % (content.tag, content.get("n", "0"))
... 
horse        2
cow         17
cowboy       2
>>> 

If I make one minor modification to the xml and change an n to an m as in my example below the getchildren will return none for none matches, how can I ignore nones?

In [2]: from lxml import etree

In [3]: xml = '''<corral><horse n="2"/><cow m="17"/> <cowboy n="2"/></corral>'''

In [4]: pen =etree.fromstring(xml)

In [5]: pencontents = pen.getchildren()

In [6]: for content in pencontents:
   ...:     print(content.get('n'))
2
None
2

Because 
In [17]: for content in pencontents:
   ....:     if content is not None:
   ....:         print(content.get('n'))

Sayth