/usr/share/doc/libplplot12/examples/c++/ is in libplplot-dev 5.10.0+dfsg-1.
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/usr/share/doc/libplplot12/examples/c++/CMakeLists.txt
/usr/share/doc/libplplot12/examples/c++/Makefile
/usr/share/doc/libplplot12/examples/c++/README.qt_example
/usr/share/doc/libplplot12/examples/c++/plc++demos.h
/usr/share/doc/libplplot12/examples/c++/qt_PlotWindow.cpp
/usr/share/doc/libplplot12/examples/c++/qt_PlotWindow.h
/usr/share/doc/libplplot12/examples/c++/qt_example.cpp
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