cc -O2 -pipe  -pthread  -Wall -Wextra -Werror=implicit-function-declaration monetary/strfmon.c -o monetary/strfmon -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread 
monetary/strfmon.c:3:10: fatal error: 'monetary.h' file not found
    3 | #include <monetary.h>
      |          ^~~~~~~~~~~~
1 error generated.