python lxml迭代如何处理标记文本？

Question

我关注code：

from lxml import etree
from io import StringIO

html = """"Hello, world!"<span class="black">
<div class="c1">division
    <p>"Hello - this is me.
    (c) passage in division"
    <b>"bold in passage "</b>
    </p>
        My phone:
    (+7) 999-999-99-99
</div>
<!-- Comment -->
<pre>It's a pre.</pre>
"""

def parse_HTML(html):
    parser = etree.HTMLParser()
    root = etree.parse(StringIO(html), parser)

    for elem in root.getiterator():
        # skip comments, their type == class 'cython_function_or_method'
        if type(elem.tag) is not str:
            continue
        if elem.text is None:
            text = ''
        else:
            text = elem.text

        print(str(elem.tag) + " => " + text)

if __name__ == "__main__":
    parse_HTML(html)

输出：

html =>
body =>
p => "Hello, world!"
span =>

div => division

p => "Hello - this is me.
    (c) passage in division"

b => "bold in passage "
<class 'cython_function_or_method'>
pre => It's a pre.

问题： 为何选择“我的手机：         （+7）999-999-99-99“输出中不存在？