def check_required_keys(self, required_keys):
h = self._contents_hash<EOL>for key in required_keys:<EOL><INDENT>if key not in h:<EOL><INDENT>raise InsufficientGraftMPackageException("<STR_LIT>" % key)<EOL><DEDENT><DEDENT>
raise InsufficientGraftMPackageException if this package does not
        conform to the standard of the given package