Function frame_support::storage::hashed::get_or

pub fn get_or<T, HashFn, R>(hash: &HashFn, key: &[u8], default_value: T) -> Twhere
    T: Decode + Sized,
    HashFn: Fn(&[u8]) -> R,
    R: AsRef<[u8]>,

Return the value of the item in storage under key, or default_value if there is no explicit entry.