 Complete the following phrase:  Lynna Irby born December 6, 1998 is an American track and field sprinter who competes in the 100m, 200m, and 400m dash events. At the 400m dash, she set an all-time world record at the age of 12 running 54.57 before becoming the fastest American 400m high school runner in the last 20 years. She gained 16 national titles from Jr Olympic and Youth National meets. Irby has won silver medals in the event at both the 2015 World Youth Championships and the 