/// Pops the next item with its index, if one is available.
Pops the next item with its index, if one is available.
Pops the next item with its index if one is available .
pub fn pop(&mut self) -> Option<(StreamIndex, T)> {
        self.queue.pop_front().map(|msg| {
            let index = self.begin;
            self.begin.inc_assign();
            (index, msg)
        })
    }
pub fn pop ( & mut self ) -> Option < ( StreamIndex , T ) > { self . queue . pop_front ( ) . map ( | msg | { let index = self . begin ; self . begin . inc_assign ( ) ; ( index , msg ) } ) }
Pops the next item with its index, if one is available.
Pops the next item with its index if one is available .
&mut self