Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Treasury Stock (Details)

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Stockholders' Equity - Treasury Stock (Details) - USD ($)
12 Months Ended
Oct. 16, 2020
Apr. 30, 2021
Apr. 30, 2020
Schedule Of Stockholders Equity [Line Items]      
Treasury stock (in shares)   155,486 16,667
Treasury stock, value   $ 1,817,414 $ 70,000
Treasury shares cancelled (in shares) 16,667    
Retirement of treasury stock   0  
Treasury Stock      
Schedule Of Stockholders Equity [Line Items]      
Retirement of treasury stock $ 70,000 $ (70,000)