src/components/layouts/index.js

import Single from './Single/Single';

import TopBottom from './TopBottom/TopBottom';

import LeftRight from './LeftRight/LeftRight';

import LeftTopBottom from './LeftTopBottom/LeftTopBottom';

export default {
  SingleLayout: Single,

  TopBottomLayout: TopBottom,

  LeftRightLayout: LeftRight,

  LeftTopBottomLayout: LeftTopBottom,
};