def _unused_label(self, label):
original = label<EOL>existing = self.labels<EOL>i = <NUM_LIT:2><EOL>while label in existing:<EOL><INDENT>label = '<STR_LIT>'.format(original, i)<EOL>i += <NUM_LIT:1><EOL><DEDENT>return label<EOL>
Generate an unused label.