code: func (api *Client) DeleteFileContext(ctx context.Context, fileID string) (err error) {
  	values := url.Values{
  		"token": {api.token},
  		"file":  {fileID},
  	}
  
  	_, err = api.fileRequest(ctx, "files.delete", values)
  	return err
  }
docs: // DeleteFileContext deletes a file with a custom context