pub unsafe extern "C" fn rocksdb_writebatch_delete_range_cf(
    b: *mut rocksdb_writebatch_t,
    column_family: *mut rocksdb_column_family_handle_t,
    start_key: *const c_char,
    start_key_len: usize,
    end_key: *const c_char,
    end_key_len: usize
)