def read_element_using_argtuple(self, argtuple):
<EOL>if self.format == FMT_DELIMITED:<EOL><INDENT>return None<EOL><DEDENT>node = self.cfg_dict<EOL>for key in argtuple:<EOL><INDENT>node = node[key]<EOL><DEDENT>return node<EOL>
takes a tuple of keys
returns node found in cfg_dict
found by traversing cfg_dict by successive 
application of keys from element_path