set(key, value) {
        if (isPlainObject(key)) {
            Object.assign(this.values, key);
            return this;
        }

        // Setting a value to null removes it from the config
        if (value === null) {
            delete this.values[key];
            return this;
        }

        _set(this.values, key, value);
        return this;
    }
Sets a value in the config.
If 'value' is null, removes the key from the config

@param {string} key Key to set
@param {any} value Value to set at `key`
@return Config This config instance

@method get
@public