Function size_prefixed_root_as_postscript 

pub fn size_prefixed_root_as_postscript(
    buf: &[u8],
) -> Result<Postscript<'_>, InvalidFlatbuffer>

Verifies that a buffer of bytes contains a size prefixed Postscript and returns it. Note that verification is still experimental and may not catch every error, or be maximally performant. For the previous, unchecked, behavior use size_prefixed_root_as_postscript_unchecked.