XML 40 R29.htm IDEA: XBRL DOCUMENT v3.22.0.1
Note 3 – Marketable Securities (Tables)
 9 Months Ended
Jan. 31, 2022
Investments, Debt and Equity Securities [Abstract]  
[custom:ScheduleOfAmortizedCostNetUnrealizedGainLossFairValues]
   Amortized Cost  Net Unrealized Gains (Losses)  Fair Value
Money market funds  $1,598,428   $1,108   $1,599,536 
Asset-backed securities   3,113,823    (21,984)   3,091,839 
Corporate bonds   44,387,966    (633,039)   43,754,927 
Total  $49,100,217   $(653,915)  $48,446,302 
[custom:ScheduleOfContractualMaturitiesFairValueMeasurements]
   One Year or Less  One to
Five Years		  Over Five Years  Total
Money market funds  $1,599,536   $—     $—     $1,599,536 
Asset-backed securities   —      3,091,839    —      3,091,839 
Corporate bonds   19,808,158    23,366,723    580,046    43,754,927 
Total  $21,407,694   $26,458,562   $580,046   $48,446,302 
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
   Level 1  Level 2  Level 3  Total
Money market funds  $1,599,536   $—     $—     $1,599,536 
Asset-backed securities   —      3,091,839    —      3,091,839 
Corporate bonds   —      43,754,927    —      43,754,927 
Total  $1,599,536   $46,846,766   $—     $48,446,302