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Fair value measurement
3 Months Ended
Mar. 31, 2021
Fair value measurement [Abstract]  
Fair value measurement
13.
Fair value measurement:

The carrying amounts reflected in the consolidated balance sheets of cash and cash equivalents, accounts receivables, net, other current assets, trade and other payables, due from/to related parties, other current liabilities, income tax payable and convertible promissory notes, approximate their respective fair values due to the short maturity of these instruments.