code: func (b *DynamoDBBackend) Delete(ctx context.Context, key []byte) error {
  	if len(key) == 0 {
  		return trace.BadParameter("missing parameter key")
  	}
  	if _, err := b.getKey(ctx, key); err != nil {
  		return err
  	}
  	return b.deleteKey(ctx, key)
  }
docs: // Delete deletes item by key