pub fn get_targets<'a, Iter, I, T, U>( targets: Iter, fallback: Option<(&'a dyn Fn(U) -> Option<&'a T>, U)>, ) -> Result<Vec<&'a T>, TargetInvalid>where Iter: ExactSizeIterator<Item = &'a I>, I: AsRef<str> + 'a, T: TargetTrait<'a>,