Create a UNTL file.

        Writes file to supplied file path.

def create_xml_file(self, untl_filename):
        """Create a UNTL file.

        Writes file to supplied file path.
        """
        try:
            f = open(untl_filename, 'w')
            f.write(self.create_xml_string().encode('utf-8'))
            f.close()
        except:
            raise UNTLStructureException(
                'Failed to create UNTL XML file. File: %s' % (untl_filename)
            )