Function pallet_elections_phragmen::migrations::v5::pre_migrate_fn

pub fn pre_migrate_fn<T: Config>(to_migrate: Vec<T::AccountId>) -> Box<dyn Fn()>

Given the list of voters to migrate return a function that does some checks and information prior to migration. This can be linked to [frame_support::traits::OnRuntimeUpgrade:: pre_upgrade] for further testing.