Avoiding const?

[ixid]

I apologize for what I'm sure is a very basic question. How 
should I do this elegantly?

        bool set[char[]];
        //Stuff
        char[][] words = set.keys;
It gives the error:
Error: cannot implicitly convert expression (set.keys()) of type 
const(char)[][] to char[][]
and I'm not sure why I can't copy const data to normal data.