code: def get_write_cache(self):
      
      if self._options.write_to and not self._write_cache:
        cache_spec = self._resolve(self._sanitize_cache_spec(self._options.write_to))
        if cache_spec:
          with self._cache_setup_lock:
            self._write_cache = self._do_create_artifact_cache(cache_spec, 'will write to')
      return self._write_cache
docs: Returns the write cache for this setup, creating it if necessary.
  
      Returns None if no write cache is configured.