Function truncate_zero_be_bytes 

pub fn truncate_zero_be_bytes(
    mem_bytes: &[u8],
    disk_len: usize,
) -> Option<&[u8]>

Truncates mem_bytes to disk_len, by removing zero bytes from the start of the slice. Used to discard unused zero bytes during serialization.

Return None if any of the truncated bytes are non-zero

Panics

• if mem_bytes is shorter than disk_len.