lib/plugins/aws/lib/cloudformationSchema.js/yamlType
const yamlType = (name, kind) => {
  const functionName = _.includes(['Ref', 'Condition'], name) ? name : `Fn::${name}`;
  return new YAML.Type(`!${name}`, {
    kind,
    construct: data => {
      if (name === 'GetAtt') {
        // special GetAtt dot syntax
        return { [functionName]: _.isString(data) ? _.split(data, '.', 2) : data };
      }
      return { [functionName]: data };
    },
  });
};