EXHIBIT 99.1 - EXPLANATION OF RESPONSES

 (7)  On June 1, 2017, the Issuer amended and restated its certificate of
incorporation to modify certain variable rate adjustment provisions applicable
to the conversion ratios of the Series E, Series E-1 and Series F Preferred
Stock, and to create two new series of preferred stock, designated Series E-2
Preferred Stock and Series F-2 Preferred Stock (the "June Reclassification").
Immediately prior to the June Reclassification, the Issuer's certificate of
incorporation provided for a variable rate adjustment provision which provided
that, if the IPO Price is less than $47.826108, the number of shares of Common
Stock issuable to a holder of Series E Preferred Stock and/or Series E-1
Preferred Stock upon automatic conversion in connection with the IPO, would be
determined by multiplying (a) the conversion price of the Series E and/or Series
E-1 Preferred Stock held by such holder by (b) a fraction, the numerator of
which would be the IPO Price, and the denominator of which would be $47.826108
(the "Series E Variable Rate Adjustment Provision") and also provided that in
the event the Issuer completes a qualified IPO in which the IPO Price is less
than $48.444 per share,  the number of shares of Common Stock issuable to a
holder of Series F Preferred Stock upon automatic conversion in connection with
the IPO, would be determined by multiplying (a) the conversion price of the
Series F Preferred Stock held by such holder by (b) a fraction, the numerator of
which would be the IPO Price, and the denominator of which would be $48.444 (the
"Series F Variable Rate Adjustment Provision"). Pursuant to the June
Reclassification, the Series E Variable Rate Adjustment Provision and the Series
F Variable Rate Adjustment Provision were replaced with fixed conversion rate
provisions, which provided that, in the event that the Issuer's IPO occurs on or
prior to July 30, 2017, the number of shares of Common Stock issuable upon
automatic conversion in connection with the IPO would be determined: (A) with
respect to holders of Series E Preferred Stock, by multiplying the number of
shares of Series E Preferred Stock held by such holder by a fraction, the
numerator of which would be $43.47828, and the denominator of which would be
$14.49276, (B) with respect to holders of Series E-1 Preferred Stock, by
multiplying the number of shares of Series E-1 Preferred Stock held by such
holder by a fraction, the numerator of which would be $43.47828, and the
denominator of which would be $25.84704, and (C) with respect to holders of
Series F Preferred Stock, by multiplying the number of Shares of Series F
Preferred Stock held by such holder by a fraction, the numerator of which would
be $44.04, and the denominator of which would be $14.68002. The June
Reclassification was structured to comply with Rule 16b-3 of the Securities
Exchange Act of 1934, as amended.