zope xml error

while i worked with xml in zope using python i got the following error.



Error Type: AttributeError
Error Value: documentElement


i've installed pyxml,xmllib ,xmldocument .

can anyone shed some light

thanks in advance
Jinu

my python script is as follows

import string
doc=getattr(con text,'addressbo ok.xml')
#doc=context.ob jectvalues('add ressbook.xml')
book=doc.docume ntElement # here the error is generated.
print "Number of items",len(book .childNodes)
names=[]
for item in book.childNodes :
name=item.first Child
names.append(na me.firstChild.n odeValue)
print "Names",string. join(names,",")
return printed

addressbook.xml

<?xml version="1.0"?>
<addressbook>
<item>
<name>Bob </name>
<address>2118 Wildhare st </address>
</item>
<item>
<name>Randolf </name>
<address>13 E. Roundway</address>
</item>
</addressbook>