docs: function findModulePath(filename_rootfile, filename, options = DEFAULT_OPTIONS) {
      /**
       * . 相对路径
       * . 绝对路径
       */
      const ext = path.extname(filename);
      if (ext && exports.extensions.indexOf(ext) === -1) {
          return null;
      }
      if (path.dirname(filename_rootfile) !== filename_rootfile) {
          filename_rootfile = path.dirname(filename_rootfile);
      }
      const storeKey = storePathKey(filename_rootfile, filename);
      const storeKeyVal = store.get(storeKey);
      const { baseUrl = DEFAULT_OPTIONS.baseUrl } = options;
      if (storeKeyVal) {
          return storeKeyVal === "null" ? null : storeKeyVal;
      }
      // save result path and return pathname
      const storeAndReturn = (rpath) => {
          store.set(storeKey, String(rpath));
          return rpath;
      };
      const roots = baseUrl.concat(filename_rootfile);
      let r = null;
      roots.some(baseRoot => {
          if (ext) {
              const namepath = genPath(baseRoot, filename);
              r = namepath;
              return !!namepath;
          }
          let namepath2 = null;
          exports.extensions.some(extname => {
              namepath2 = genPath(baseRoot, `${filename}${extname}`);
              if (!namepath2) {
                  namepath2 = genPath(baseRoot, `${filename}/index${extname}`);
              }
              return !!namepath2;
          });
          if (namepath2) {
              r = namepath2;
              return true;
          }
          return false;
      });
      return storeAndReturn(r);
  }