Function pallet_roles::storage::hashed::take_or_else   
pub fn take_or_else<T, F, HashFn, R>(
    hash: &HashFn,
    key: &[u8],
    default_value: F
) -> Twhere
    T: Decode,
    F: FnOnce() -> T,
    HashFn: Fn(&[u8]) -> R,
    R: AsRef<[u8]>,Expand description
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.