current_time      804 tutorial/lesson_09_update_definitions.cpp         double t1 = current_time();
current_time      903 tutorial/lesson_09_update_definitions.cpp         double t2 = current_time();
current_time      911 tutorial/lesson_09_update_definitions.cpp         double t3 = current_time();
current_time      212 tutorial/lesson_12_using_the_gpu.cpp             double t1 = current_time();
current_time      222 tutorial/lesson_12_using_the_gpu.cpp             double t2 = current_time();
current_time       30 tutorial/lesson_16_rgb_run.cpp     double t_new = current_time();