Annual report pursuant to Section 13 and 15(d)

Income Taxes (Deferred Tax Asset Valuation Allowance Rollforward) (Details)

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Income Taxes (Deferred Tax Asset Valuation Allowance Rollforward) (Details) - USD ($)
12 Months Ended
Apr. 30, 2019
Apr. 30, 2018
Income Tax Disclosure [Abstract]    
Valuation allowance, beginning of year $ (7,837,755) $ (9,471,662)
Decrease (increase) during period (2,213,279) 1,633,907
Valuation allowance, ending balance $ (10,051,034) $ (7,837,755)