Function parse 

pub fn parse(
    cursor: &mut Cursor<'_>,
    offset_size: u8,
    _length_size: u8,
    msg_size: usize,
) -> Result<SharedMessage>

Parse a shared message wrapper.

The type_field indicates how the message is shared:

• 0 or 2: shared in another object header (version-dependent)
• 1 or 3: shared in the SOHM