require(module) {
		const path = this.resolver.fs.resolve('.');
		let mod = this._cacheRequireModule;
		if (!mod || mod.path !== path) {
			const filename = this.resolver.fs.join(path, '/vm.js');
			mod = new (this._Module)(filename, path);
			this.resolver.registerModule(mod, filename, path, null, false);
			this._cacheRequireModule = mod;
		}
		return this._requireImpl(mod, module, true);
	}
Require a module in VM and return it's exports.

@public
@param {string} module - Module name.
@return {*} Exported module.
@throws {*} If the module couldn't be found or loading it threw an error.