code: def _open_file(cls, writer_spec, filename_suffix, use_tmp_bucket=False):
      
      if use_tmp_bucket:
        bucket = cls._get_tmp_gcs_bucket(writer_spec)
        account_id = cls._get_tmp_account_id(writer_spec)
      else:
        bucket = cls._get_gcs_bucket(writer_spec)
        account_id = cls._get_account_id(writer_spec)
  
      # GoogleCloudStorage format for filenames, Initial slash is required
      filename = "/%s/%s" % (bucket, filename_suffix)
  
      content_type = writer_spec.get(cls.CONTENT_TYPE_PARAM, None)
  
      options = {}
      if cls.ACL_PARAM in writer_spec:
        options["x-goog-acl"] = writer_spec.get(cls.ACL_PARAM)
  
      return cloudstorage.open(filename, mode="w", content_type=content_type,
                               options=options, _account_id=account_id)
docs: Opens a new gcs file for writing.