page(contents, cfiBase, start, end) {
    var root = contents && contents.document ? contents.document.body : false;
    var result;

    if (!root) {
      return;
    }

    result = this.rangePairToCfiPair(cfiBase, {
      start: this.findStart(root, start, end),
      end: this.findEnd(root, start, end)
    });

    if (this._dev === true) {
      let doc = contents.document;
      let startRange = new _epubcfi__WEBPACK_IMPORTED_MODULE_0__[/* default */ "a"](result.start).toRange(doc);
      let endRange = new _epubcfi__WEBPACK_IMPORTED_MODULE_0__[/* default */ "a"](result.end).toRange(doc);
      let selection = doc.defaultView.getSelection();
      let r = doc.createRange();
      selection.removeAllRanges();
      r.setStart(startRange.startContainer, startRange.startOffset);
      r.setEnd(endRange.endContainer, endRange.endOffset);
      selection.addRange(r);
    }

    return result;
  }
Find CFI pairs for a page
@param {Contents} contents Contents from view
@param {string} cfiBase string of the base for a cfi
@param {number} start position to start at
@param {number} end position to end at