It has to stay under 2**64-1 so it makes sense to change the data type from `BigEndianInt` into `u64`. Currently it can't be done because of https://github.com/althea-mesh/serde-rlp/issues/10 which should improve serialization of primitive types like u64.
It has to stay under 2**64-1 so it makes sense to change the data type from
BigEndianIntintou64.Currently it can't be done because of althea-net/serde-rlp#10 which should improve serialization of primitive types like u64.