biobulkbende.org/node_modules/node-sass/src/libsass/docs/api-importer-internal.md

// External import entry
struct Sass_Import {
  char* imp_path; // path as found in the import statement
  char *abs_path; // path after importer has resolved it
  char* source;
  char* srcmap;
  // error handling
  char* error;
  size_t line;
  size_t column;
};

// Struct to hold importer callback
struct Sass_Importer {
  Sass_Importer_Fn importer;
  double           priority;
  void*            cookie;
};