| Schedule of Basic and Diluted Earnings Per Share | 
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 | 
   
 | 
 Voting common stock 
 | 
   
 | 
   
 | 
 Non-voting common stock 
 | 
   
 | 
 
| 
 Basic net loss per share: 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Numerator 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Allocation of undistributed losses attributable to common stockholders 
 | 
   
 | 
 $ 
 | 
 (5,380 
 | 
 ) 
 | 
   
 | 
 $ 
 | 
 (2,105 
 | 
 ) 
 | 
 
| 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Denominator 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Weighted average number of shares used in basic per share computation 
 | 
   
 | 
   
 | 
 16,379,788 
 | 
   
 | 
   
 | 
   
 | 
 6,409,519 
 | 
   
 | 
 
| 
 Net loss per share, basic 
 | 
   
 | 
 $ 
 | 
 (0.33 
 | 
 ) 
 | 
   
 | 
 $ 
 | 
 (0.33 
 | 
 ) 
 | 
 
| 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Diluted net loss per share: 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Numerator 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Allocation of undistributed losses for basic computation 
 | 
   
 | 
 $ 
 | 
 (5,380 
 | 
 ) 
 | 
   
 | 
 $ 
 | 
 (2,105 
 | 
 ) 
 | 
 
| 
 Reallocation of undistributed losses as a result of conversion of 
     non-voting to voting common shares 
 | 
   
 | 
   
 | 
 (2,105 
 | 
 ) 
 | 
   
 | 
   
 | 
 — 
 | 
   
 | 
 
| 
 Allocation of undistributed losses 
 | 
   
 | 
 $ 
 | 
 (7,485 
 | 
 ) 
 | 
   
 | 
 $ 
 | 
 (2,105 
 | 
 ) 
 | 
 
| 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Denominator 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Weighted average number of shares used in basic per share computation 
 | 
   
 | 
   
 | 
 16,379,788 
 | 
   
 | 
   
 | 
   
 | 
 6,409,519 
 | 
   
 | 
 
| 
 Add: conversion of non-voting to voting common shares outstanding 
 | 
   
 | 
   
 | 
 6,409,519 
 | 
   
 | 
   
 | 
   
 | 
 — 
 | 
   
 | 
 
| 
 Weighted average number of shares used in diluted per share computation 
 | 
   
 | 
   
 | 
 22,789,307 
 | 
   
 | 
   
 | 
   
 | 
 6,409,519 
 | 
   
 | 
 
| 
 Net loss per share, diluted 
 | 
   
 | 
 $ 
 | 
 (0.33 
 | 
 ) 
 | 
   
 | 
 $ 
 | 
 (0.33 
 | 
 ) 
 | 
 
 
 
  
For the three months ended March 31, 2019, basic and diluted net loss per share is: 
| 
   
 | 
   
 | 
 Common stock 
 | 
   
 | 
 
| 
 Basic and diluted net loss per share: 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Numerator 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Net loss attributable to common stockholders 
 | 
   
 | 
 $ 
 | 
 (8,858 
 | 
 ) 
 | 
 
| 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Denominator 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Weighted average number of shares used in basic and 
     diluted per share computation 
 | 
   
 | 
   
 | 
 1,464,572 
 | 
   
 | 
 
| 
 Net loss per share, diluted 
 | 
   
 | 
 $ 
 | 
 (6.05 
 | 
 ) 
 | 
 
 
 
  
 | 
| Schedule of Antidilutive Shares Excluded from Calculation of Diluted Net Loss Per Share | 
 The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive:  
| 
   
 | 
   
 | 
 As of March 31, 
 | 
   
 | 
 
| 
   
 | 
   
 | 
 2020 
 | 
   
 | 
   
 | 
 2019 
 | 
   
 | 
 
| 
 Convertible preferred stock 
 | 
   
 | 
   
 | 
 — 
 | 
   
 | 
   
 | 
   
 | 
 19,356,835 
 | 
   
 | 
 
| 
 Stock options to purchase common stock 
 | 
   
 | 
   
 | 
 2,657,704 
 | 
   
 | 
   
 | 
   
 | 
 1,304,285 
 | 
   
 | 
 
| 
 Non-vested common stock 
 | 
   
 | 
   
 | 
 1,158,185 
 | 
   
 | 
   
 | 
   
 | 
 2,382,651 
 | 
   
 | 
 
| 
   
 | 
   
 | 
   
 | 
 3,815,889 
 | 
   
 | 
   
 | 
   
 | 
 23,043,771 
 | 
   
 | 
 
 
 
  
 |