fn next_back_index(&self) -> usize {
        let rem = self.iter.len() % (self.step + 1);
        if self.first_take {
            if rem == 0 { self.step } else { rem - 1 }
        } else {
            rem
        }
    }
// The zero-based index starting from the end of the iterator of the
// last element. Used in the `DoubleEndedIterator` implementation.
The zero-based index starting from the end of the iterator of the
last element. Used in the `DoubleEndedIterator` implementation.
The zero - based index starting from the end of the iterator of the last element . Used in the ` DoubleEndedIterator ` implementation .
fn next_back_index(&self) -> usize {
        let rem = self.iter.len() % (self.step + 1);
        if self.first_take {
            if rem == 0 { self.step } else { rem - 1 }
        } else {
            rem
        }
    }
fn next_back_index ( & self ) -> usize { let rem = self . iter . len ( ) % ( self . step + 1 ) ; if self . first_take { if rem == 0 { self . step } else { rem - 1 } } else { rem } }
The zero-based index starting from the end of the iterator of the
last element.
The zero - based index starting from the end of the iterator of the last element .
&self