Better support for types

[isaiahtaylorhh]

Hello all, I hope you'll entertain an enhancement request. I'm enjoying the library so far but I'm wondering if we can get better type accuracy. One specific example would be:

get(key: string): Promise<any>;

Promise<any> could be clarified with X | Y | null, allowing for null checking, as that may often return null.

Thanks!

[mlynch]

Thanks, will think about how to enable this in the next v3 release. Some kind of generic type could work here I think...