def set_prefix(self, elt, pyobj):
if isinstance(pyobj, tuple):<EOL><INDENT>namespaceURI,localName = pyobj<EOL>self.prefix = elt.getPrefix(namespaceURI)<EOL><DEDENT>
use this method to set the prefix of the QName,
        method looks in DOM to find prefix or set new prefix.
        This method must be called before get_formatted_content.