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2. ACCOUNTS RECEIVABLE, NET (Tables)
 12 Months Ended
Dec. 31, 2020
Accounts Receivable, after Allowance for Credit Loss [Abstract]  
Changes in the allowance for doubtful accounts
   Year ended December 31,
   2020  2019
Balance at Beginning of Period  $10,000   $10,000 
Charged to costs and expenses   —      —   
Write-offs, net of recoveries   —      —   
Balance at End of Period  $10,000   $10,000