text: #ifndef HITTABLE_CONSTANT_MEDIUM_H
  #define HITTABLE_CONSTANT_MEDIUM_H
  
  #include "hittable_base.h"
  #include "material_base.h"
  #include "muon_common.h"
  
  const Hittable *hittable__constant_medium__build(MemoryArena *p_memory_arena,
                                                   const Hittable *p_boundary,
                                                   double density,
                                                   const Material *p_material);
  
  #endif