def _is_optional(substructure):
if type(substructure) == _Optional:<EOL><INDENT>return True<EOL><DEDENT>if type(substructure) is dict:<EOL><INDENT>for value in substructure.values():<EOL><INDENT>if not _is_optional(value):<EOL><INDENT>return False<EOL><DEDENT><DEDENT>return True<EOL><DEDENT>return False<EOL>
Determines if a substructure is an optional part of the configuration.