/usr/include/ is in libixion-dev 0.7.0-3.
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/usr/include/libixion-0.8/
/usr/include/libixion-0.8/ixion/
/usr/include/libixion-0.8/ixion/formula_tokens.hpp
/usr/include/libixion-0.8/ixion/types.hpp
/usr/include/libixion-0.8/ixion/config.hpp
/usr/include/libixion-0.8/ixion/depends_tracker.hpp
/usr/include/libixion-0.8/ixion/model_context.hpp
/usr/include/libixion-0.8/ixion/depth_first_search.hpp
/usr/include/libixion-0.8/ixion/session_handler.hpp
/usr/include/libixion-0.8/ixion/formula_tokens_fwd.hpp
/usr/include/libixion-0.8/ixion/function_objects.hpp
/usr/include/libixion-0.8/ixion/lexer_tokens.hpp
/usr/include/libixion-0.8/ixion/exceptions.hpp
/usr/include/libixion-0.8/ixion/cell_listener_tracker.hpp
/usr/include/libixion-0.8/ixion/formula_result.hpp
/usr/include/libixion-0.8/ixion/env.hpp
/usr/include/libixion-0.8/ixion/formula.hpp
/usr/include/libixion-0.8/ixion/formula_function_opcode.hpp
/usr/include/libixion-0.8/ixion/formula_interpreter.hpp
/usr/include/libixion-0.8/ixion/mem_str_buf.hpp
/usr/include/libixion-0.8/ixion/cell_queue_manager.hpp
/usr/include/libixion-0.8/ixion/formula_name_resolver.hpp
/usr/include/libixion-0.8/ixion/global.hpp
/usr/include/libixion-0.8/ixion/cell.hpp
/usr/include/libixion-0.8/ixion/macros.hpp
/usr/include/libixion-0.8/ixion/address.hpp
/usr/include/libixion-0.8/ixion/formula_parser.hpp
/usr/include/libixion-0.8/ixion/formula_functions.hpp
/usr/include/libixion-0.8/ixion/thread.hpp
/usr/include/libixion-0.8/ixion/formula_lexer.hpp
/usr/include/libixion-0.8/ixion/interface/
/usr/include/libixion-0.8/ixion/interface/model_context.hpp
/usr/include/libixion-0.8/ixion/interface/session_handler.hpp
/usr/include/libixion-0.8/ixion/formula_opcode.hpp
/usr/include/libixion-0.8/ixion/matrix.hpp
/usr/include/libixion-0.8/ixion/column_store_type.hpp
/usr/include/libixion-0.8/ixion/hash_container/
/usr/include/libixion-0.8/ixion/hash_container/map.hpp
/usr/include/libixion-0.8/ixion/hash_container/set.hpp