Function verify_value_at_multi 

pub fn verify_value_at_multi(
    bytes: &[u8],
    ty: &TypeRepr,
    list_element: Option<ListElementKind>,
    root: usize,
    multi: MultiRegion,
) -> Result<(), VerifyError>

Multi-region sibling of verify_value_at: certify a bare value whose root pointer (and every pointer reachable from it) is an arena-absolute offset and whose graph may span regions. bytes is the whole arena slice; root is the arena-absolute offset of the value’s root header. Any escape (a span fitting no region, or running off the region it starts in) is a loud VerifyError — the decode must not run.