docs/src/modules/utils/generateMarkdown.ts/getChained
function getChained(type: PropTypeDescriptor) {
  if (type.raw) {
    const marker = 'chainPropTypes';
    const indexStart = type.raw.indexOf(marker);

    if (indexStart !== -1) {
      const parsed = docgenParse(
        `
        import PropTypes from 'prop-types';
        const Foo = () => <div />
        Foo.propTypes = {
          bar: ${recast.print(recast.parse(type.raw).program.body[0].expression.arguments[0]).code}
        }
        export default Foo
      `,
        null,
        null,
        // helps react-docgen pickup babel.config.js
        { filename: './' },
      );
      return {
        type: parsed.props.bar.type,
        required: parsed.props.bar.required,
      };
    }
  }

  return false;
}