Income taxes - Provision for income taxes (Details) - USD ($)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 202,444	$ 191,322
State	(895)	87,630
Total	201,549	278,952
Deferred:
Federal	(524,733)	(132,957)
State	(124,798)	(59,271)
Total	(649,531)	(192,228)
Total provision	$ (447,982)	$ 86,724

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