write a function read$\_$data$($filename$)$ that retrieves the data from the given file filename $($the file is in CSV format$)$ by returning every entry INCLUDING the headings $($the headings always exist in given files, this will be used later for finding indices of columns$)$ as a single list. Each entry should be a list containing data separated by a comma, and any new line characters at the end of each row should be stripped off. It's important to note that no imports should be used for this task.

You may assume there are no errors in the given and tested files.