Function frame_support::storage::child::get_or_else

pub fn get_or_else<T: Decode + Sized, F: FnOnce() -> T>(
    storage_key: &[u8], 
    child_info: ChildInfo, 
    key: &[u8], 
    default_value: F
) -> T

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