I use only three if/elif/else for this question.
Specifically, the first statement is to determine if the parameter is equal to 'a1' or 'a8' or 'h1' or 'h8'. This first if will help you return the 'Corner'.
In the second statement, I use something like
parameter to find if the first index of that string is equal to 'h' or 'a'; or
parameter to examine if the second index is equal to '1' or '8'. The statement will help you find the 'Border'
Lastly, everything else is 'Inside'