| Quarterly Financial Information (Unaudited) | 
 
 Note 14 – Quarterly Financial Information
 (Unaudited) 
 
   
 
 
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 Quarter Ended | 
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 |   | 
    | 
 August 31, | 
   | 
    | 
 November 30, | 
   | 
    | 
 February 28, | 
   | 
    | 
 May 31, | 
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 | 
  
 Year ended May 31, 2018: 
  | 
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    | 
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    | 
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    | 
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 Operating expenses 
  | 
    | 
 $ | 
 (9,807,001 | 
 )  | 
    | 
 $ | 
 (10,775,051 | 
 )  | 
    | 
 $ | 
 (14,140,507 | 
 )  | 
    | 
 $ | 
 (11,196,754 | 
 )  | 
  
 
 | 
  
 Other income (expense) 
  | 
    | 
   | 
 (361,879 | 
 )  | 
    | 
   | 
 830,022 | 
   | 
    | 
   | 
 (740,404 | 
 )  | 
    | 
   | 
 1,966,816 | 
   | 
  
 
 | 
  
 Interest expense 
  | 
    | 
   | 
 (1,459,393 | 
 )  | 
    | 
   | 
 (1,002,656 | 
 )  | 
    | 
   | 
 (3,069,189 | 
 )  | 
    | 
   | 
 (393,685 | 
 )  | 
  
 
 | 
  
 Net (loss) 
  | 
    | 
   | 
 (11,628,273 | 
 )  | 
    | 
   | 
 (10,947,685 | 
 )  | 
    | 
   | 
 (17,950,100 | 
 )  | 
    | 
   | 
 (9,623,623 | 
 )  | 
  
 
 | 
  
 Basic and diluted loss per share 
  | 
    | 
 $ | 
 (0.08 | 
 )  | 
    | 
 $ | 
 (0.07 | 
 )  | 
    | 
 $ | 
 (0.10 | 
 )  | 
    | 
 $ | 
 (0.04 | 
 )  | 
  
 
 | 
  
 Year ended May 31, 2017: 
  | 
    | 
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  | 
  | 
    | 
  | 
  | 
  | 
    | 
  | 
  | 
  | 
    | 
  | 
  | 
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 | 
  
 Operating expenses 
  | 
    | 
 $ | 
 (5,358,120 | 
 )  | 
    | 
 $ | 
 (6,156,117 | 
 )  | 
    | 
 $ | 
 (8,016,917 | 
 )  | 
    | 
 $ | 
 (7,799,580 | 
 )  | 
  
 
 | 
  
 Other income (expense) 
  | 
    | 
   | 
 3,735 | 
   | 
    | 
   | 
 1,229,114 | 
   | 
    | 
   | 
 (23,078 | 
 )  | 
    | 
   | 
 969,929 | 
   | 
  
 
 | 
  
 Interest expense 
  | 
    | 
   | 
 
 —   | 
   | 
    | 
   | 
 (540,330 | 
 )  | 
    | 
   | 
 (72,437 | 
 )  | 
    | 
   | 
 
 —   | 
   | 
  
 
 | 
  
 Net (loss) 
  | 
    | 
   | 
 (5,354,385 | 
 )  | 
    | 
   | 
 (5,467,333 | 
 )  | 
    | 
   | 
 (8,112,432 | 
 )  | 
    | 
   | 
 (6,829,651 | 
 )  | 
  
 
 | 
  
 Basic and diluted loss per share 
  | 
    | 
 $ | 
 (0.04 | 
 )  | 
    | 
 $ | 
 (0.04 | 
 )  | 
    | 
 $ | 
 (0.06 | 
 )  | 
    | 
 $ | 
 (0.05 | 
 )  | 
  
 
 | 
  
 Year ended May 31, 2016: 
  | 
    | 
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    | 
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  | 
  | 
    | 
  | 
  | 
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 Operating expenses 
  | 
    | 
 $ | 
 (6,657,481 | 
 )  | 
    | 
 $ | 
 (2,893,779 | 
 )  | 
    | 
 $ | 
 (5,049,037 | 
 )  | 
    | 
 $ | 
 (6,575,214 | 
 )  | 
  
 
 | 
  
 Other income (expense) 
  | 
    | 
   | 
 62,686 | 
   | 
    | 
   | 
 211 | 
   | 
    | 
   | 
 2,202 | 
   | 
    | 
   | 
 78,045 | 
   | 
  
 
 | 
  
 Interest expense 
  | 
    | 
   | 
 (2,300,220 | 
 )  | 
    | 
   | 
 (2,371,025 | 
 )  | 
    | 
   | 
 
 —   | 
   | 
    | 
   | 
 
 —   | 
   | 
  
 
 | 
  
 Net (loss) 
  | 
    | 
   | 
 (8,895,015 | 
 )  | 
    | 
   | 
 (5,264,593 | 
 )  | 
    | 
   | 
 (5,046,835 | 
 )  | 
    | 
   | 
 (6,497,169 | 
 )  | 
  
 
 | 
  
 Basic and diluted loss per share 
  | 
    | 
 $ | 
 (0.12 | 
 )  | 
    | 
 $ | 
 (0.06 | 
 )  | 
    | 
 $ | 
 (0.05 | 
 )  | 
    | 
 $ | 
 (0.04 | 
 )  | 
  
  
  
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