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Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Share-based Payment Arrangement, Option, Exercise Price Range (Details)

v3.20.4
Stockholders' Equity - Share-based Payment Arrangement, Option, Exercise Price Range (Details) - $ / shares
9 Months Ended
Jan. 31, 2021
Jan. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Outstanding (in shares) 1,260,213 2,776,778
Exercisable (in shares) 1,038,024 Ìý
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 | $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