Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2	Aug 2, 2017	C	4,985,647	—	A	4,985,647	I	By Vulcan Capital Venture Capital I LLC
Common Stock^F3,F2	Aug 2, 2017	C	1,373,217	—	A	6,358,864	I	By Vulcan Capital Venture Capital I LLC
Common Stock^F4,F2	Aug 2, 2017	C	232,748	—	A	6,591,612	I	By Vulcan Capital Venture Capital I LLC
Common Stock^F5,F6	Aug 2, 2017	C	223,393	—	A	223,393	I	By VCVC III LLC
Common Stock^F7,F6	Aug 2, 2017	C	206,661	—	A	430,054	I	By VCVC III LLC

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series B Preferred Stock^F2,F1	—	Aug 2, 2017	C	4,985,647	D	—	—	Common Stock	4,985,647	I
Series C Preferred Stock^F2,F3	—	Aug 2, 2017	C	1,373,217	D	—	—	Common Stock	1,373,217	I
Series D Preferred Stock^F2,F4	—	Aug 2, 2017	C	232,748	D	—	—	Common Stock	232,748	I
Series E Preferred Stock^F6,F5	—	Aug 2, 2017	C	223,393	D	—	—	Common Stock	223,393	I
Series F Preferred Stock^F6,F7	—	Aug 2, 2017	C	206,661	D	—	—	Common Stock	206,661	I

Explanation of responses

F1Each share of the issuer's Series B Preferred Stock automatically converted into 1 share of the issuer's Common Stock on August 2, 2017 in connection with the closing of the issuer's sale of its Common Stock in its firm commitment initial public offering (the "IPO") pursuant to a registration statement on Form S-1 (File No. 333-219093) under the Securities Act of 1933, as amended (the "Registration Statement"), and had no expiration date.
F2These securities are held of record by Vulcan Capital Venture Capital I LLC ("VCVC I"). Vulcan Capital Venture Capital Management I LLC ("VCVC Management I") manages VCVC I. VCVC Management I is managed by Vulcan Ventures Incorporated, which is wholly owned by Paul G. Allen, who has sole voting and investment power over the shares held by VCVC I. Mr. Allen disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.
F3Each share of the issuer's Series C Preferred Stock automatically converted into 1 share of the issuer's Common Stock on August 2, 2017 in connection with the closing of the issuer's sale of its Common Stock in its IPO pursuant to the Registration Statement, and had no expiration date.
F4Each share of the issuer's Series D Preferred Stock automatically converted into 1 share of the issuer's Common Stock on August 2, 2017 in connection with the closing of the issuer's sale of its Common Stock in its IPO pursuant to the Registration Statement, and had no expiration date.
F5Each share of the issuer's Series E Preferred Stock automatically converted into 1 share of the issuer's Common Stock on August 2, 2017 in connection with the closing of the issuer's sale of its Common Stock in its IPO pursuant to the Registration Statement, and had no expiration date.
F6These securities are held of record by VCVC III LLC ("VCVC III"). VCVC Management III LLC ("VCVC Management III") manages VCVC III. VCVC Management III is managed by Cougar Investment Holdings LLC, which is wholly owned by Paul G. Allen, who has sole voting and investment power over the shares held by VCVC III. Mr. Allen disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.
F7Each share of the issuer's Series F Preferred Stock automatically converted into 1 share of the issuer's Common Stock on August 2, 2017 in connection with the closing of the issuer's sale of its Common Stock in its IPO pursuant to the Registration Statement, and had no expiration date.