> Perhaps, you should just fix Order instances in _eval_series methods to include logx symbol.

I get it now. My previous comment does not make sense now. I fixed the issue i.e. now log(x) term is being included in big O notation but I'm facing another problem.

In _eval_series methods, when the Order is being calculated, I replace logx with C.log(x) so that the log(x) term is included. But in some tests, it gives error while substituting. Any suggestions?