old_contents: 'use strict';
  import jsTypes from 'js-types';
  
  const lowerCaseTypes = jsTypes.map(type => type.toLowerCase());
  
  /**
   * Determine if a type is JS type
   * @param {Stirng} type - type to verify
   * @return {Boolean} - type is a JS type
   */
  export default function isJsType(type) {
    if (typeof type !== 'string') {
      throw new TypeError('Expected type to be a string');
    }
  
    return lowerCaseTypes.indexOf(type.toLowerCase()) > -1;
  }
  
new_contents: 'use strict';
  import jsTypes from 'js-types';
  
  const lowerCaseTypes = jsTypes.map(type => type.toLowerCase());
  
  /**
   * Determine if a type is JS type
   * @param {Stirng} type - type to verify
   * @return {Boolean} - type is a JS type
   */
  module.exports = function isJsType(type) {
    if (typeof type !== 'string') {
      throw new TypeError('Expected type to be a string');
    }
  
    return lowerCaseTypes.indexOf(type.toLowerCase()) > -1;
  };
  
subject: use module.exports instead of default