Annual report pursuant to Section 13 and 15(d)

Assumptions used to estimate fair value of stock warrants granted (Details)

v3.22.2
Assumptions used to estimate fair value of stock warrants granted (Details) - Warrant Assumptions Used [Member]
12 Months Ended
Apr. 30, 2022
Apr. 30, 2021
Class of Warrant or Right [Line Items]    
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum 0.79% 0.52%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum 0.85% 2.87%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term 5 years 3 years 5 months 1 day
[custom:SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm2] 5 years 4 years 6 months
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum 222.45% 211.02%
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum 223.17% 292.28%