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Note 4 - Intangible Assets (Tables)
6 Months Ended
Jun. 30, 2021
Notes Tables  
Schedule of Finite-Lived Intangible Assets [Table Text Block]
  

June 30,

2021

  

December 31,

2020

 
         

Lighting patent

 $6,797,000  $6,797,000 

Accumulated amortization

  (2,053,259)  (1,840,853)
         

Net

 $4,743,741  $4,956,147