[JOINT FILING AGREEMENT This Joint Filing Agreement may be executed in any number of counterparts, all of which together shall constitute one and the same instrument. Xiaomi Ventures Limited Xiaomi Corporation] [CUSIP No. 98419E108 1 Name of Reporting Person]

[CUSIP No. 98419E108 1. Names of reporting persons Morningside Technology Investments Limited 2. Check the appropriate box if a member of a group ¨ ¨ (a) 3. SEC use only 4. Citizenship or place of organization British Virgin Islands Number of shares beneficially owned by each reporting person with 5. Sole voting power 0 6. Shared voting power 37,787,905 (See]

[Joint Filing Agreement [Remainder of this page has been left intentionally blank.] Shenglong Zou Vantage Point Global Limited Shenglong Zou Director Choice & Chance Limited For and on behalf of Choice & Chance Limited David Connor Authorized Signer, President of Brennan Limited, as officer of Choice & Chance Limited] [CUSIP No.: 98419E108 (1) Name of reporting persons Shenglong Zou (“Mr. Zou”) (2) Check the appropriate box if a member of a group* ¨ ¨ (a) (3) SEC use only (4) Citizenship or place of organization People’s Republic of China Number of shares beneficially owned by each reporting person with (5) Sole voting power 32,814,606 Common Shares (6) Shared voting]

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