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Summary of Significant Accounting Policies (Details Narrative) - USD ($) | 6 Months Ended |  |
--- | --- | --- | ---
Oct. 31, 2021 | Oct. 31, 2020 | Apr. 30, 2021 | Aug. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Cash and Cash Equivalents, at Carrying Value | $ 72,630,000 |  | $ 83,028,000 |
Revenue remaining performance obligation | $ 300,000 |  |  |
Revenue remaining performance obligation, percentage | 100.00% |  |  |
Performance obligation revenue of next twelve months | $ 300,000 |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | 4,928,474 | 5,540,469 |  |
Santander Bank [Member] |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Letters of credit issued amount | $ 258,000 |  |  |
Santander Bank [Member] | Letter 2 [Member] |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Letters of credit issued amount | 64,000 |  |  |
Santander Bank [Member] | Letter 2 [Member] | August 2020 [Member] |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Letters of credit outstanding, amount |  |  |  | $ 323,000
Foreign Financial Institutions [Member] |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Cash and Cash Equivalents, at Carrying Value | 32,000 |  |  |
Restricted Cash and Security Agreements [Member] | Santander Bank [Member] | Letter of Credit [Member] |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Deposits | 157,000 |  |  |
Restricted Cash and Security Agreements [Member] | Santander Bank [Member] | Letter 1 [Member] |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Letters of credit outstanding, amount | 126,000 |  |  |
Restricted Cash and Security Agreements [Member] | Santander Bank [Member] | Letter 2 [Member] |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Letters of credit outstanding, amount | $ 645,000 |  |  |

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