Function peek_input_until_with_offset 

pub fn peek_input_until_with_offset<R, O, P>(
    reader: &mut R,
    buffer: &mut [u8],
    offset: usize,
    timeout: Option<Duration>,
    predicate: P,
) -> impl Future<Output = PeekOutput<O>>
where
    R: AsyncRead + Unpin,
    P: Fn(&[u8]) -> Option<O>,

Same as peek_input_until but with a starting offset as peek-size.

It is assumed that the offst is within the buffer boundaries, but it will be clamped to the buffer.len() regardless.

Uses the buffer-derived attempt budget; see peek_input_until_with_options when you need an explicit budget.