pub fn with_hashed_key(self) -> TreeInstruction {
        match self {
            Self::Read(key) => TreeInstruction::Read(key.hashed_key_u256()),
            Self::Write(entry) => TreeInstruction::Write(TreeEntry {
                key: entry.key.hashed_key_u256(),
                value: entry.value,
                leaf_index: entry.leaf_index,
            }),
        }
    }
Maps the key preimage in this instruction to a hashed key used by the Merkle tree.
core/lib/merkle_tree/src/domain.rs