Move Error

// Works:
fn sum<T: Zero>(list: &Vec<T>) -> T {
    list.iter().fold(Zero::zero(), |a: T, b| a + *b)
}

// Does not work:
// Gives a move error on &b saying you are trying to move out
// of a dereference of an &-pointer.
fn sum<T: Zero>(list: &Vec<T>) -> T {
    list.iter().fold(Zero::zero(), |a: T, &b| a + b)
}