Annual report pursuant to Section 13 and 15(d)

Note 10 - Summary of Stock Options - Valuation Assumption for Employee Stock Purchase Plan (Details)

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Note 10 - Summary of Stock Options - Valuation Assumption for Employee Stock Purchase Plan (Details)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Expected term (Year) 5 years 5 years
Average volatility 73.00% 59.00%
Risk-free interest rate 2.65% 1.89%
Dividend yield 0.00% 0.00%
2017 Employee Stock Purchase Plan [Member]    
Expected term (Year) 91 days 91 days
Average volatility 72.00% 61.00%
Risk-free interest rate 1.92% 1.06%
Dividend yield 0.00% 0.00%