fn combine(&mut self) -> Option<f32> {
        let mut sum = match self.source.next() { Some(s) => s, _ => return None };

        for _ in 1..self.from {
            sum += self.source.next().unwrap_or(0.);
        }

        Some(sum)
    }
// Combine channel samples into one mono sample (e.g. from=2, to=1).
Combine channel samples into one mono sample .
Combine channel samples into one mono sample .
fn combine(&mut self) -> Option<f32> {
        let mut sum = match self.source.next() { Some(s) => s, _ => return None };
        for _ in 1..self.from {
            sum += self.source.next().unwrap_or(0.);
        }
        Some(sum)
    }
fn combine ( & mut self ) -> Option < f32 > { let mut sum = match self . source . next ( ) { Some ( s ) => s , _ => return None } ; for _ in 1 .. self . from { sum += self . source . next ( ) . unwrap_or ( 0. ) ; } Some ( sum ) }
Combine channel samples into one mono sample (e.g.
Combine channel samples into one mono sample ( e . g .
&mut self
&mut self