/usr/ is in ruby-gnuplot 2.4.1-2.
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/usr/share/doc/ruby-gnuplot/
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/usr/share/doc/ruby-gnuplot/examples/3d_surface_plot.rb
/usr/share/doc/ruby-gnuplot/examples/histogram.rb
/usr/share/doc/ruby-gnuplot/examples/output_image_file.rb
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