How to set the "depth" of the tree when generating comments?

Question

Ruby on Rails

Good afternoon!
It is necessary to create a test data generator for the comments table; when generating, you must set the number of comments and the maximum "depth" of these comments, i.e. The maximum number of replies per replies to a comment.
So, please tell me how, when generating these very comments, you can set the "depth" of comments?
Thanks in advance for your replies, sorry if I didn't explain well!