text: 
  #include <ftw.h>
  
  #include <bits/ensure.h>
  
  int ftw(const char *, int (*fn)(const char *, const struct stat *, int), int) {
  	(void)fn;
  	__ensure(!"ftw() not implemented");
  	__builtin_unreachable();
  }
  
  int nftw(const char *, int (*fn)(const char *, const struct stat *, int, struct FTW *),
  		int, int) {
  	(void)fn;
  	__ensure(!"nftw() not implemented");
  	__builtin_unreachable();
  }
  
  