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4. INVENTORIES (Tables)
9 Months Ended
Jan. 31, 2019
Inventory Disclosure [Abstract]  
Schedule of inventories
  

January 31,

2019

  

April 30,

2018

 
Raw materials  $8,660   $8,165 
Work-in-process       7,964 
Total inventories  $8,660   $16,129