xpath is not a function #504

When I look in your examples in the README file I see the following line:

select = require("xml-crypto").xpath

However, when I use this code I get an error about select not being a function. When I look into the code it appears that xpath is not being exported so select is undefined.

Is this a mistake in the example or a mistake in the code. I am seeing a lot of other issues where people are using require("xml-crypto").xpath but seemingly not having the same issue I am. I tried to look through the commit history to see if maybe it was being exported in a previous version but I didn't spot it (yet). Maybe I am just doing something wrong, not sure.