code: def test_clear(self):
      kvs = [("foo", "bar"), ("1234", "5678")]
      with dbm.ndbm.open(self.filename, "c") as db:
          for k, v in kvs:
              db[k] = v
              self.assertIn(k, db)
          self.assertEqual(len(db), len(kvs))
  
          db.clear()
          for k, v in kvs:
              self.assertNotIn(k, db)
          self.assertEqual(len(db), 0)
  
imports: from test.support import import_helper
  from test.support import os_helper
  import os
  import unittest
  import dbm.ndbm
  from dbm.ndbm import error
label_desc: Use image node_id 18 for calling the DbmTestCase obj's underlying member method code with example usage: obj.test_clear() without return types