POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and
appoints Louis S. Citron, Timothy Schaller, Sasha Keough and Stephanie Brecher,
and each of them, with full power to act without the others, his or her true and
lawful attorney-in-fact, with full power of substitution, to sign any and all
instruments, certificates and documents that may be necessary, desirable or
appropriate to be executed on behalf of himself as an individual or in his or
her capacity as a direct or indirect general partner, director, officer or
manager of any partnership, corporation or limited liability company, pursuant
to section 13 or 16 of the Securities Exchange Act of 1934, as amended (the
"Exchange Act"), and any and all regulations promulgated thereunder, and to file
the same, with all exhibits thereto, and any other documents in connection
therewith, with the Securities and Exchange Commission, and with any other
entity when and if such is mandated by the Exchange Act or by the Financial
Industry Regulatory Authority, granting unto said attorney-in-fact full power
and authority to do and perform each and every act and thing necessary,
desirable or appropriate, fully to all intents and purposes as he or she might
or could do in person, thereby ratifying and confirming all that said
attorney-in-fact, or his or her substitutes, may lawfully do or cause to be done
by virtue hereof.

IN WITNESS WHEREOF, this Power of Attorney has been signed as of the 13th day of
March, 2017.

/s/ M. James Barrett
/s/ Peter J. Barris
/s/ Forest Baskett
/s/ Ali Behbahani
/s/ Colin Bryant
/s/ Carmen Chang
/s/ Anthony A. Florence, Jr.
/s/ Carol G. Gallagher
/s/ Dayna Grayson
/s/ Patrick J. Kerins
/s/ P. Justin Klein
/s/ Vanessa Larco
/s/ Joshua Makower
/s/ Mohamad H. Makhzoumi
/s/ Edward T. Mathers
/s/ David M. Mott
/s/ Sara M. Nayeem
/s/ Jason R. Nunn
/s/ Gregory Papadopoulos
/s/ Chetan Puttagunta
/s/ Jon Sakoda
/s/ Scott D. Sandell
/s/ A. Brooke Seawell
/s/ Peter W. Sonsini
/s/ Melissa Taunton
/s/ Frank M. Torti
/s/ Ravi Viswanathan
/s/ Paul E. Walker
/s/ Rick Yang