pub fn into_previous(mut self) -> Self
    {
        self.as_next().as_next();
        self
    }
/// Walk to the previous half-edge in the adjacent face.
Walk to the previous half-edge in the adjacent face.
Walk to the previous half - edge in the adjacent face .
pub fn into_previous(mut self) -> Self
    {
        self.as_next().as_next();
        self
    }
pub fn into_previous ( mut self ) -> Self { self . as_next ( ) . as_next ( ) ; self }
Walk to the previous half-edge in the adjacent face.
Walk to the previous half - edge in the adjacent face .
mut self
mut self