Thank you for making this awsome package!

While using haven to read SAS7BDAT file, I found that haven will not read the creation/modified time of the file. The rationale of getting these two timestamps is that these two timestamps stored in the metadata of a SAS7BDAT file are different from the timestamps read the OS.

And in ReadStat, there are already two functions, readstat_get_creation_time and readstat_get_modified_time, which can be used to read the creation/modified time. But they are not exposed in haven yet.

My proposal is that maybe we can add these two timestamps to the attribute of the output.

I forked haven and have made a commit to add creation/modified time to the output's attribute here for you kind review. I compared the creation/modified time read by readstat_get_creation_time and readstat_get_modified_time and the creation/modified time obtained by PROC CONTENT from my end. The result shows that they are identical.

If you find my implementation workable, I can make a pull request to haven.

Thank you!
Jack