Function pallet_roles::storage::unhashed::take_or_else

pub fn take_or_else<T, F>(key: &[u8], default_value: F) -> Twhere
    T: Decode,
    F: FnOnce() -> T,

Return the value of the item in storage under key, or default_value() if there is no explicit entry. Ensure there is no explicit entry on return.