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Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Schedule of Outstanding and Exercisable Warrants (Details)

v3.21.2
Stockholders' Equity - Schedule of Outstanding and Exercisable Warrants (Details) - $ / shares
12 Months Ended
Apr. 30, 2021
Apr. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Outstanding (in shares) 1,214,473 Ìý
Exercisable (in shares) 1,032,411 2,734,899
Warrant Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Outstanding (in shares) 374,174 566,223
Warrant Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Exercisable (in shares) 374,174 Ìý
Warrant | Warrant Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Outstanding (in shares) 374,174 Ìý
Warrant | $4.89 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 4.89 Ìý
Maximum exercise price (in dollars per share) 4.89 Ìý
Weighted average exercise price (in dollars per share) $ 4.89 Ìý
Outstanding (in shares) 50,000 Ìý
Weighted average exercise price (in dollars per share) $ 4.89 Ìý
Weighted average remaining life (in years) 3 years 5 months 8 days Ìý
Exercisable (in shares) 50,000 Ìý
Warrant | $6.00 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 6.00 Ìý
Maximum exercise price (in dollars per share) 6.00 Ìý
Weighted average exercise price (in dollars per share) $ 6.00 Ìý
Outstanding (in shares) 100,000 Ìý
Weighted average exercise price (in dollars per share) $ 6.00 Ìý
Weighted average remaining life (in years) 3 years 1 month 2 days Ìý
Exercisable (in shares) 100,000 Ìý
Warrant | $6.87 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 6.87 Ìý
Maximum exercise price (in dollars per share) 6.87 Ìý
Weighted average exercise price (in dollars per share) $ 6.87 Ìý
Outstanding (in shares) 224,174 Ìý
Weighted average exercise price (in dollars per share) $ 6.87 Ìý
Weighted average remaining life (in years) 1 year 5 months 23 days Ìý
Exercisable (in shares) 224,174 Ìý