code: def test_return_empty_bytestring(self):
      cur = self.con.execute("select X''")
      val = cur.fetchone()[0]
      self.assertEqual(val, b"")
  
imports: import datetime
  import unittest
  import sqlite3
  import weakref
  import functools
  from test import support
  from unittest.mock import patch
  from .util import memory_database, cx_limit
  from .util import MemoryDatabaseMixin
label_desc: Use image node_id 31 for calling the RegressionTests obj's underlying member method code with example usage: obj.test_return_empty_bytestring() without return types