Recently I was browsing through the questions of the site and this question caught my attention. To me it seemed to be very clear and an interesting question but for some unknown reason the question was downvoted (even though $1$ time). I am wondering whether there is really anything wrong mathematically in the post. Can someone enlighten me?
As one of the people who answered the question in its initial form (but haven't and won't be downvoting it), I thought I'd weigh in on why someone might downvote a question like that. If you go to the effort to figure out and write up a nice answer to the question, only to have that question change and that answer no longer make sense, that can be potentially frustrating (I've held off editing my answer until the issue with definitions is cleared up entirely, which has now happened; but I won't have time to fix my answer until tomorrow).
It's an unfortunate fact that quite a few terms and definitions in topology are used rather inconsistently and worse yet, in some cases it can be very hard to determine if a different looking definition is actually equivalent to the one you know/are working with or not (especially for a novice learning topology for the first time). (Sidenote: Topologists really need to establish a set of standardized terms for the many separation axioms and points related to sequences that have been defined).