pub unsafe extern "C" fn rocksdb_transactiondb_get_cf(
txn_db: *mut rocksdb_transactiondb_t,
options: *const rocksdb_readoptions_t,
column_family: *mut rocksdb_column_family_handle_t,
key: *const c_char,
keylen: usize,
vallen: *mut usize,
errptr: *mut *mut c_char
) -> *mut c_char