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10. Net Loss per Share (Tables)
12 Months Ended
Dec. 31, 2020
Earnings Per Share [Abstract]  
Schedule of antidilutive stock
   December 31, 
   2020   2019 
Options to purchase common stock   2,570    2,659 
Nonvested restricted stock units   9,699    14,945 
Warrants to purchase common stock   3,579,284    480,035 
Total   3,591,553    497,639