Element tree errors

[saif.shakeel at gmail.com]

HI,
       The following code is for replacing the strings localid with
"datapackageid" in an xml document.:

from xml.etree.ElementTree import ElementTree as et

file_input = raw_input("Enter The ODX File Path:")
(shortname,ext)=os.path.splitext(file_input)
test_file=shortname+"testxml.xml"

input_xml = open(file_input,'r')

tree = et.parse(input_xml)

for t in tree.getiterator("SERVICEPARAMETER"):
        if t.get("Semantics") == "localId":
                t.set("Semantics", "dataPackageID")

tree.write(test_file)

                     The python ver is 2.5.there is no module error
now,but when i run i get this error:

Traceback (most recent call last):
  File "C:\Documents and Settings\pzchfr\Desktop\test.py", line 12, in
<module>
    tree = et.parse(input_xml)
TypeError: unbound method parse() must be called with ElementTree
instance as first argument (got file instance instead)

                  I am passing the input file from user to be parsed
which seems to be incorrect,Can someone help me.
              Thanks