4. Leases (Details - Components of lease) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Lessee Disclosure [Abstract]
Operating lease cost	$ 788	$ 798	$ 2,364	$ 2,570
Variable lease cost	112	155	433	488
Short-term lease cost	99	83	289	83
Total lease cost	$ 999	$ 1,036	$ 3,086	$ 3,141