如何从帮助文件的“另见”部分中提取函数名称？例如：来自“另见”部分的 object=help(lm) ：
‘summary.lm’ for summaries and ‘anova.lm’ for the ANOVA table;
‘aov’ for a different interface.
The generic functions ‘coef’, ‘effects’, ‘residuals’, ‘fitted’,
‘vcov’.
‘predict.lm’ (via ‘predict’) for prediction, including confidence
and prediction intervals; ‘confint’ for confidence intervals of
_parameters_.
我想要一个函数名称向量 - "summary.lm","anova.lm","coef" ...