Nah she wrote 3! The exclamation point is a mathematical expression called factorial which is basically adding up all positive whole numbers below that number. So here it's 3+2+1 which equals 6. So ...
#include "rtc_base/platform_thread_types.h" #include "rtc_base/thread_annotations.h" // See notes in the 'Performance' unit test for the effects of this flag. #define ...