pub fn extend(&mut self, entries: &[TreeEntry]) -> anyhow::Result<BatchOutput> {
        let (output, _) = self.extend_inner(entries, None)?;
        Ok(output)
    }
Extends this tree by creating its new version.

All keys in the provided entries must be distinct.

# Return value

Returns information about the update such as the final tree hash.

# Errors

Proxies database I/O errors.
core/lib/zk_os_merkle_tree/src/lib.rs