# How to prove a Language is neither a Computably enumerable nor Co-Computably enumerable?

What would be the general approach for that? And what are the things that generally overlooked while proving such things?

For example,

I have a Language, L ={e:$L(M_e)$ such that it accepts only 'a where a$\in \sum^{*}$}?

Is it possible,
1. To prove its not a CE, Can we reduce $(Acceptance\space problem)^{complement}$ to L?
2. To prove its not a Co-CE, Can we reduce Acceptance problem to L?