Function sp_trie::read_child_trie_value

pub fn read_child_trie_value<L: TrieConfiguration, DB>(
    keyspace: &[u8], 
    db: &DB, 
    root_slice: &[u8], 
    key: &[u8]
) -> Result<Option<Vec<u8>>, Box<TrieError<L>>> where
    DB: HashDBRef<L::Hash, DBValue>, 

Read a value from the child trie.