Exhibit 99.1
JOINT FILING AGREEMENT
Pursuant to Rule 13d-1(k)(1) promulgated under the Securities Exchange Act of 1934, as amended, the undersigned agree that the Statement on Schedule 13G and any amendments thereto to which this exhibit is attached is filed on behalf of each of them.
| Date: January 28, 2019 |
| YAOH WDAI LTD | |||
| By: | /s/ Hong Yao | ||
| Name: | Hong Yao | ||
| Title: | Authorized Signatory | ||
| YAOH WDAI HOLDING LTD. | |||
| By: | /s/ Hong Yao | ||
| Name: | Hong Yao | ||
| Title: | Authorized Signatory | ||
| Hong Yao | |||
| /s/ Hong Yao | |||
| Name: | Hong Yao | ||
