code: function includeFile(path, options) {
    var opts = utils.shallowCopy({}, options);
    if (!opts.filename) {
      throw new Error('`include` requires the \'filename\' option.');
    }
    opts.filename = exports.resolveInclude(path, opts.filename);
    return handleCache(opts);
  }
docs: Get the template function.
  
  If `options.cache` is `true`, then the template is cached.
  
  @memberof module:ejs-internal
  @param {String}  path    path for the specified file
  @param {Options} options compilation options
  @return {(TemplateFunction|ClientFunction)}
  Depending on the value of `options.client`, either type might be returned
  @static