Function take_some_while_window

pub fn take_some_while_window<I, F>(
    input: &mut Pear<I>,
    n: usize,
    f: F,
) -> Result<I::Many, I>
where
    I: Input + Rewind,
    F: FnMut(&I::Slice) -> bool,

Consumes tokens while cond matches on a window of tokens of size n and returns them. Fails if there no tokens match, otherwise returns all of the tokens before the first failure.