Overlapping Histogram in R

While preparing a class exercise involving the use of overlaying of histogram, I searched Google on possible article or discussion on the said topic. Luckily, I found a blog where the author demonstrated an R function to create an overlapping histogram. However, a comment from a guy also showed the same output using transparency. Below were the sample codes that can be used to generate overlapping histogram in R as based on the blog and the viewers comment.

                                                                                                                                     

                                                                                                                        

Here are the codes: