/usr/include/boost/functional/ is in libboost1.62-dev 1.62.0+dfsg-5.
This file is owned by root:root, with mode 0o755.
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/usr/include/boost/functional/factory.hpp
/usr/include/boost/functional/forward_adapter.hpp
/usr/include/boost/functional/hash/
/usr/include/boost/functional/hash.hpp
/usr/include/boost/functional/hash/detail/
/usr/include/boost/functional/hash/detail/float_functions.hpp
/usr/include/boost/functional/hash/detail/hash_float.hpp
/usr/include/boost/functional/hash/detail/limits.hpp
/usr/include/boost/functional/hash/extensions.hpp
/usr/include/boost/functional/hash/hash.hpp
/usr/include/boost/functional/hash/hash_fwd.hpp
/usr/include/boost/functional/hash_fwd.hpp
/usr/include/boost/functional/lightweight_forward_adapter.hpp
/usr/include/boost/functional/overloaded_function/
/usr/include/boost/functional/overloaded_function.hpp
/usr/include/boost/functional/overloaded_function/config.hpp
/usr/include/boost/functional/overloaded_function/detail/
/usr/include/boost/functional/overloaded_function/detail/base.hpp
/usr/include/boost/functional/overloaded_function/detail/function_type.hpp
/usr/include/boost/functional/value_factory.hpp