| Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis | 
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June 30, 2021  | 
 
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Level 1  | 
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Level 2  | 
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Level 3  | 
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Total Fair Value  | 
 
Cash equivalents:  | 
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Money Market Funds  | 
$  | 
 11,564,000  | 
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$  | 
 —  | 
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$  | 
 —  | 
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$  | 
 11,564,000  | 
 
Subtotal  | 
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 11,564,000  | 
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 —  | 
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 —  | 
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 11,564,000  | 
 
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Short-term investments:  | 
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Corporate Notes/Bonds  | 
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 —  | 
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 1,705,000  | 
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 —  | 
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 1,705,000  | 
 
Subtotal  | 
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 —  | 
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 1,705,000  | 
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 —  | 
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 1,705,000  | 
 
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Long-term investments:  | 
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Corporate Notes/Bonds  | 
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 —  | 
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 4,523,000  | 
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 —  | 
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 4,523,000  | 
 
Convertible debt  | 
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 —  | 
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 —  | 
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 374,000  | 
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 374,000  | 
 
Subtotal  | 
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 —  | 
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 4,523,000  | 
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 374,000  | 
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 4,897,000  | 
 
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Total  | 
$  | 
 11,564,000  | 
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$  | 
 6,228,000  | 
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$  | 
 374,000  | 
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$  | 
 18,166,000  | 
 
  
  
  
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December 31, 2020  | 
 
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Level 1  | 
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Level 2  | 
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Level 3  | 
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Total Fair Value  | 
 
Cash equivalents:  | 
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Money Market Funds  | 
$  | 
 9,424,000  | 
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$  | 
 —  | 
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$  | 
 —  | 
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$  | 
 9,424,000  | 
 
Subtotal  | 
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 9,424,000  | 
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 —  | 
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 —  | 
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 9,424,000  | 
 
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Short-term investments:  | 
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Commercial Paper  | 
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 —  | 
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 700,000  | 
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 —  | 
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 700,000  | 
 
Corporate Notes/Bonds  | 
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 —  | 
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 2,059,000  | 
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 —  | 
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 2,059,000  | 
 
Subtotal  | 
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 —  | 
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 2,759,000  | 
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 —  | 
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 2,759,000  | 
 
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Long-term investments:  | 
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Corporate Notes/Bonds  | 
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 —  | 
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 5,605,000  | 
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 —  | 
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 5,605,000  | 
 
Convertible debt  | 
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 —  | 
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 —  | 
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 605,000  | 
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 605,000  | 
 
Subtotal  | 
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 —  | 
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 5,605,000  | 
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 605,000  | 
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 6,210,000  | 
 
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Current Liabilities:  | 
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Contingent Consideration  | 
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 —  | 
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 —  | 
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 (550,000)  | 
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 (550,000)  | 
 
Subtotal  | 
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 —  | 
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 —  | 
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 (550,000)  | 
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 (550,000)  | 
 
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Total  | 
$  | 
 9,424,000  | 
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$  | 
 8,364,000  | 
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$  | 
 55,000  | 
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$  | 
 17,843,000  | 
 
  
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