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Note I - Stock-based Compensation - Options Valuation Assumptions (Details)
3 Months Ended
Jul. 31, 2020
Jul. 31, 2019
Expected term (years) (Year) 5 years 6 months 5 years 6 months
Risk-free interest rate 0.36% 2.28%
Volatility 50.00% 39.00%
Dividend yield 0.00% 0.00%