/usr/lib/python2.7/dist-packages/sage/monoids/ is in sagemath-common 7.4-9.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/python2.7/dist-packages/sage/monoids/__init__.py
/usr/lib/python2.7/dist-packages/sage/monoids/all.py
/usr/lib/python2.7/dist-packages/sage/monoids/automatic_semigroup.py
/usr/lib/python2.7/dist-packages/sage/monoids/free_abelian_monoid.py
/usr/lib/python2.7/dist-packages/sage/monoids/free_abelian_monoid_element.py
/usr/lib/python2.7/dist-packages/sage/monoids/free_monoid.py
/usr/lib/python2.7/dist-packages/sage/monoids/free_monoid_element.py
/usr/lib/python2.7/dist-packages/sage/monoids/hecke_monoid.py
/usr/lib/python2.7/dist-packages/sage/monoids/indexed_free_monoid.py
/usr/lib/python2.7/dist-packages/sage/monoids/monoid.py
/usr/lib/python2.7/dist-packages/sage/monoids/string_monoid.py
/usr/lib/python2.7/dist-packages/sage/monoids/string_monoid_element.py
/usr/lib/python2.7/dist-packages/sage/monoids/string_ops.py