text: #ifndef LEVELS_H
  #define LEVELS_H
  #include <aterm1.h>
  
  void SG_cleanupLevels(void);
  void SG_initLevels(void);
  void SG_setLevel(ATerm t, int level);
  void SG_unsetLevel(ATerm t);
  int SG_getLevel(ATerm t);
  
  #endif
  