Common Stock Warrants  | 
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| Common Stock Warrants | 
 9. Common Stock Warrants As of March 31, 2021 and December 31, 2020, the following common stock warrants were outstanding:  
  During the first quarter of 2021, the Company issued 4,917 shares of common stock through a cashless exercise of the February 2016 common stock warrants held by Torreya Partners LLC.       | 
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- References No definition available. 
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- Definition Common stock warrant. No definition available. 
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