cpython/Lib/test/xmltestdata/c14n-20/c14nComment.xml

<dsig:CanonicalizationMethod xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:c14n2="http://www.w3.org/2010/xml-c14n2" Algorithm="http://www.w3.org/2010/xml-c14n2">
 <c14n2:IgnoreComments>true</c14n2:IgnoreComments>
</dsig:CanonicalizationMethod>