from lxml import etree

myXML = "data.xml"
tree = etree.parse(myXML)
root = tree.getroot()
for node in root:
    if node.tag == "basic" or node.tag == "expert":
        user = [None] * 4
        for i, child in enumerate(node):
            if child.tag == "name":
                user[0] = i
                user[1] = child.text
            if child.tag == "email":
                user[2] = i
                user[3] = child.text
        print user
        if user[3].startswith('_'):
            # do some other things with data if email begins with _ ...

[0, 'f.bar', 1, 'foobar@me.com']
[0, 'm.bob', 3, 'm.bob@email.com']
[0, 'm.bab', 3, 'm.bab@email.com']

<?xml version="1.0"?>
<users>
    <id>11111</id>
    <checked>True</checked>
    <version>A12</mode>
    <basic>
        <name>f.bar</name>
        <email>foobar@me.com</email>
        <forename>Foo</forename>
        <surname>Bar</surname>
    </basic>
    <expert>
        <name>m.bob</name>
        <forename>Mak</forename>
        <surname>Bob</surname>
        <email>m.bob@email.com</password>
    </expert>
    <expert>
        <name>m.bab</name>
        <forename>Mak</forename>
        <surname>Bab</surname>
        <email>m.bab@email.com</password>
    </expert>
    <guru>
        <name>e.guru</name>
        <forename>Nick</forename>
        <email>nick@email.com</password>
        <surname>Gru</surname>
    </guru>
</users>