def get_widget_document_file(widget_id, document_id, file_path=nil)
      response = Echochamber::Request.get_widget_document_file(token, widget_id, document_id)
      unless file_path.nil?
        file = File.new(file_path, 'wb')
        file.write(response)
        file.close
      end
      response
    end
def get_widget_document_file(widget_id, document_id, file_path=nil)
      response = Echochamber::Request.get_widget_document_file(token, widget_id, document_id)
      unless file_path.nil?
        file = File.new(file_path, 'wb')
        file.write(response)
        file.close
      end
      response
    end
Retrieves the file stream of a document of a widget

 @param widget_id [String]
 @param document_id [String]
 @param file_path [String] File path where to save the document.  If none is given, nothing will be saved to file.
 @return [String] Raw file stream