/usr/lib/python3/dist-packages/lxml/isoschematron/ is in python3-lxml 3.3.3-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/python3/dist-packages/lxml/isoschematron/__init__.py
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/rng/
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/rng/iso-schematron.rng
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/RNG2Schtrn.xsl
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/XSD2Schtrn.xsl
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_abstract_expand.xsl
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_dsdl_include.xsl
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_message.xsl
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_skeleton_for_xslt1.xsl
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_svrl_for_xslt1.xsl
/usr/lib/python3/dist-packages/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/readme.txt