def METHOD_NAME(self):
    # Write the <worksheet> element. This is the root element.
    schema = "http://schemas.openxmlformats.org/"
    xmlns = schema + "spreadsheetml/2006/main"
    xmlns_r = schema + "officeDocument/2006/relationships"
    attributes = [("xmlns", xmlns), ("xmlns:r", xmlns_r)]
    self._xml_start_tag("chartsheet", attributes)