Moved the dictionary look up into a function of its own. This allows us to use the same logic to call dictionary functions from within a dictionary function, by using the convenient `this.call` function.

Usage example:

    this.call('isSet', true);

First argument is the name of the key in the dictionary, the second argument is the value.

Neat stuff like the error handler should work correctly if we access the directory from within the directory like this.