Redefining `K2State`, adding methods and tests from `K2StateTest`

[YvanGuifo]

Definition that an initial state can be true

[coveralls]

Pull Request Test Coverage Report for Build 2305594050

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 40.244%

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Totals
Change from base Build 2299913950:	0.0%
Covered Lines:	5835
Relevant Lines:	14499

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💛 - Coveralls