Function write_balance
pub fn write_balance<T, AccountId>()where
    T: Unbalanced<AccountId>,
    <T as Inspect<AccountId>>::Balance: AtLeast8BitUnsigned + Debug,
    AccountId: AtLeast8BitUnsigned,Expand description
Tests Unbalanced::write_balance.
We don’t need to test the Error case for this function, because the trait makes no assumptions about the ways it can fail. That is completely an implementation detail.