cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration sys_resource/setpriority.c -o sys_resource/setpriority -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lnetwork -lbsd -latomic
sys_resource/setpriority.c: In function 'main':
sys_resource/setpriority.c:16:25: error: 'NZERO' undeclared (first use in this function)
   16 |         if ( priority < NZERO - 1 )
      |                         ^~~~~
sys_resource/setpriority.c:16:25: note: each undeclared identifier is reported only once for each function it appears in