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Fair Value Measurements (Tables) | 3 Months Ended
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Jul. 31, 2020
Fair Value Disclosures [Abstract] |
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions | The Company determined the fair value using the Black-Scholes option pricing model with the following assumptions:
|  | July 31, 2020 |  |  | July 31, 2019 |
Dividend rate |  |  | 0.0 | % |  |  | 0.0 | %
Risk-free rate |  |  | 0.1 | % |  |  | 1.9 | %
Expected life (years) |  |  | 1.0 - 1.4 |  |  |  | 2.0 - 2.4 |
Expected volatility |  |  | 101.8 | % |  |  | 111.3 | %

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- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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