Note 4 - Stock-based Compensation	3 Months Ended
Jul. 31, 2021
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	4. STOCK-BASED COMPENSATION During the three months ended July 31, 2021, options to purchase 12,600 shares of common stock were exercised at a weighted average exercise price of $4.61. At July 31, 2021, options to purchase 548,500 shares of common stock at a weighted average exercise price of $17.92 per share were outstanding and stock-based awards to purchase 5,399,004 shares of common stock were available for grant.

The entire disclosure for share-based payment arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-URI http://asc.fasb.org/topic&trid=2228938

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