Function iter_blocking 

pub fn iter_blocking<B, I>(buf_size: B, iter: I) -> RecvStream<'static, I::Item>
where
    B: Into<BufSize>,
    I: 'static + IntoIterator + Send,
    I::Item: Send,

Converts an Iterator into a Stream by consuming the iterator in a blocking thread.

It is useful when consuming the iterator is computationally expensive and involves blocking code. It prevents blocking the asynchronous context when consuming the returned stream.