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Account Receivable, Contract Assets, and Contract Liabilities - Schedule of Accounts Receivable, Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands | Oct. 31, 2020 | Apr. 30, 2020
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Account Receivable Contract Assets And Contract Liabilities |  |
Accounts receivables |  | $ 105
Contract assets | 97 | 251
Contract liabilities | $ 109 | $ 100

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