ref: 3a0d5f41a8253b4a3fbb6ae4b6ca77789fd6ae83 dir: /sys/src/ape/lib/ap/gen/abs.c/
#include <stdlib.h> int abs(int a) { if(a < 0) return -a; return a; } long labs(long a) { if(a < 0) return -a; return a; }