fn storage_target_at(
arena: &[DebugNode],
node_index: usize,
step_index: usize,
slot: U256,
space: StorageSpace,
) -> Option<StorageTarget>fn storage_target_at(
arena: &[DebugNode],
node_index: usize,
step_index: usize,
slot: U256,
space: StorageSpace,
) -> Option<StorageTarget>