text: #ifndef _ex22_h
  #define _ex22_h
  
  extern int THE_SIZE;
  //make THE_AGE available to other .c files.
  
  int get_age();
  void set_age(int age);
  //get and set an internal variable in ex22.c
  
  //updates a static variable that's inside update_ratio
  double	update_ratio(double ratio);
  void	print_size();
  #endif
  