v3.20.2
Income taxes: (Details) - Provision for Income Taxes - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Provision for Income Taxes [Abstract]      
Computed expected benefit of income taxes $ (1,891,163) $ (865,648) $ (966,289)
Stock-based compensation 1,286,201 332,082 68,037
Non-deductible interest expense 25,722 25,658 52,648
Impact of change in tax rate 5,163,267 0
Expiry of tax credits 18,486
True up of prior year balances 37,917
Increase (decrease) in valuation allowance 522,837 (4,655,359) 845,604
Income tax provision $ 0