NewSimple creates a new simple dao using the provided backend store.

ErrAlreadyExists is returned when the transaction exists in dao.

ErrHasConflicts is returned when the transaction is in the list of conflicting transactions which are already in dao.

ErrInternalDBInconsistency is returned when the format of the retrieved DAO record is unexpected.

Simple is memCached wrapper around DB, simple DAO implementation.

Version represents the current dao version.

NativeContractCache is an interface representing cache for a native contract.