pub unsafe extern "C" fn rocksdb_key_may_exist(
    db: *mut rocksdb_t,
    options: *const rocksdb_readoptions_t,
    key: *const c_char,
    key_len: usize,
    value: *mut *mut c_char,
    val_len: *mut usize,
    timestamp: *const c_char,
    timestamp_len: usize,
    value_found: *mut c_uchar
) -> c_uchar