text: typedef int (*rs_mod_will_write_file)(const char *filename);
  typedef void * (*rs_mod_ctx_init)(const char *filename);
  typedef void (*rs_mod_finish_file)(void *ctx);
  
  typedef struct rs_module_s {
      rs_mod_will_write_file  accept;
      rs_mod_ctx_init         init;
      rs_mod_finish_file      finish;
      readstat_callbacks_t    handle;
  } rs_module_t;
  
  