await Promise.all(this.src().map(async (source: Source): Promise<void> => {
			const options = {
				...this.options,
				...source.options
			};

			const sizes = arrayUniq(source.sizes.filter(/./.test, /^\d{2,4}x\d{2,4}$/i));
			const keywords = arrayDiffer(source.sizes, sizes);

			this.urls.push(source.url);

			if (sizes.length === 0 && keywords.includes('w3counter')) {
				return this.resolution(source.url, options);
			}

			if (keywords.length > 0) {
				return this.viewport({url: source.url, sizes, keywords}, options);
			}

			for (const size of sizes) {
				this.sizes.push(size);
				// TODO: Make this concurrent
				this.items.push(await this.create(source.url, size, options));
			}

			return undefined;
		}));

	private async viewport(viewport: Viewport, options: Options): Promise<void> {
		for (const item of await viewportListMem(viewport.keywords) as {size: string}[]) {
			this.sizes.push(item.size);
			viewport.sizes.push(item.size);
		}

		for (const size of arrayUniq(viewport.sizes)) {
			this.items.push(await this.create(viewport.url, size, options));
		}
	}

const getNpmPaths = function () {
	if (process.env.NODE_PATH) {
		return process.env.NODE_PATH.split(path.delimiter);
	}

	require('fix-path')();

	// Get the npm path from the user env variables.
	const paths = process.env.PATH.split(path.delimiter).map(item => path.join(item, '..', 'lib', 'node_modules'));

	// Default paths for each system
	if (win32) {
		paths.push(path.join(process.env.APPDATA, 'npm', 'node_modules'));
	} else {
		paths.push('/usr/lib/node_modules');
	}

	try {
		// Somehow `npm get prefix` does not return the correct value
		const userconfig = childProcess.execSync('npm get userconfig', {encoding: 'utf8'}).toString().trim();
		const content = fs.readFileSync(userconfig).toString('utf8');
		const match = content.match(new RegExp(`prefix=(.*?)${EOL}`));

		if (match) {
			if (win32) {
				paths.push(path.join(match[1], 'node_modules'));
			} else {
				paths.push(path.join(match[1], 'lib', 'node_modules'));
			}
		}
	} catch (err) {

	}

	return uniq(paths.reverse());
};