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(7) Shareholders' Equity (Details - Assumptions)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Equity [Abstract]      
Expected life (years) 4 years 3 days 4 years 7 days 3 years 11 months 26 days
Risk-free interest rate 0.25% 1.53% 2.74%
Volatility 73.00% 37.00% 34.00%
Expected dividend yield 0.00% 0.00% 0.00%