Quarterly report pursuant to Section 13 or 15(d)

Common Stock, Preferred Stock and Warrants - Assumptions used to estimate fair value of warrants (Details)

v3.20.4
Common Stock, Preferred Stock and Warrants - Assumptions used to estimate fair value of warrants (Details) - Warrants
6 Months Ended
Oct. 31, 2020
Expected volatility, minimum 89.00%
Expected volatility, maximum 95.00%
Expected dividends 0.00%
Expected term, minimum 4 years 11 months 1 day
Expected term, maximum 5 years
Risk-free interest rate, minimum 0.27%
Risk-free interest rate, maximum 0.29%