Note 12 - Derivatives (Tables)

3 Months Ended

Jul. 31, 2021

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

Risk-free interest rate	0.52 - 0.69	%
Expected dividend yield	-
Expected term (in years)	4.17 - 4.50
Expected volatility	211.02 - 219.34	%

Schedule of Derivative Liabilities at Fair Value [Table Text Block]

Derivative liability at April 30, 2021	$	2,812,767
Eliminated upon exercise of warrants		(163,141	)
Changes in fair value, primarily related to decrease in Company's stock price		(154,248	)
Derivative liability at July 31, 2021	$	2,495,378