Function sp_state_machine::key_changes_proof

pub fn key_changes_proof<'a, H: Hasher, Number: BlockNumber>(
    config: ConfigurationRange<'a, Number>, 
    storage: &dyn Storage<H, Number>, 
    begin: Number, 
    end: &AnchorBlockId<H::Out, Number>, 
    max: Number, 
    storage_key: Option<&PrefixedStorageKey>, 
    key: &[u8]
) -> Result<Vec<Vec<u8>>, String> where
    H::Out: Codec, 

Returns proof of changes of given key at given blocks range. max is the number of best known block.