pub fn get_or_else<T, F, HashFn, R>(
    hash: &HashFn,
    key: &[u8],
    default_value: F
) -> T
where T: Decode + Sized, 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.