Traceback (most recent call last):
 File "./xml.py", line 13, in <module>
 fn.text = values
 File "src/lxml/etree.pyx", line 1018, in lxml.etree._Element.text.__set__
 File "src/lxml/apihelpers.pxi", line 710, in lxml.etree._setNodeText
 File "src/lxml/apihelpers.pxi", line 698, in lxml.etree._createTextNode
 File "src/lxml/apihelpers.pxi", line 1491, in lxml.etree._utf8
TypeError: Argument must be bytes or unicode, got 'list'

values = base64.b64encode(values)

Traceback (most recent call last):
 File "./xml.py", line 10, in <module>
   values = base64.b64encode(values)
 File "/usr/lib/python2.7/base64.py", line 54, in b64encode
   encoded = binascii.b2a_base64(s)[:-1]
 TypeError: b2a_base64() argument 1 must be string or buffer, not list

<FileName>['1235362363151512d12d']</FileName>

<FileName>1235362363151512d12d</FileName>

#!/usr/bin/python

from lxml import etree as ET
root = ET.Element("alphanumeric")
file = open("alphanumeric.txt", "r")

for aline in file:
        values = aline.split()
        length = len(values)
        child = ET.SubElement(root,"child")

        fn = ET.SubElement(child, "FileName")
        fn.text = values
        tree = ET.ElementTree(root)
tree.write("filename.xml")

x = ET.parse("filename.xml")
print ET.tostring(x, pretty_print=True)