This adds a rule to formally verify that the `SlotState` and
`RequestState` of any given `Slot` or `Request` does not change more
than once per function call.
Closes#129
This invariant ensures that the total supply of the used token in the
contract is always greater equal to the sum of all balances within the
token combined.
This commit adds CVL rule that formally verifies the state changes of
any given request in relation to the functions of the contract that can
cause them.
Closes#128
r4bbit