Quarterly report pursuant to Section 13 or 15(d)

Assumptions used to estimate fair values of stock warrants granted

v3.21.2
Assumptions used to estimate fair values of stock warrants granted - Warrant Fair Value [Member]
3 Months Ended
Jul. 31, 2021
Class of Warrant or Right [Line Items]  
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum 211.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum 223.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate 0.00%
[custom:SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1Minimum] 4 years 2 months 1 day
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term 5 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum 0.52%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum 0.85%