code: def testDel(self):
      hparams = hparam.HParams(aaa=1, b=2.0)
  
      with self.assertRaises(ValueError):
          hparams.set_hparam("aaa", "will fail")
  
      with self.assertRaises(ValueError):
          hparams.add_hparam("aaa", "will fail")
  
      hparams.del_hparam("aaa")
      hparams.add_hparam("aaa", "will work")
      self.assertEqual("will work", hparams.get("aaa"))
  
      hparams.set_hparam("aaa", "still works")
      self.assertEqual("still works", hparams.get("aaa"))
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from tensor2tensor.utils import hparam
  import tensorflow.compat.v1
label_desc: Use image node_id 32 for calling the HParamsTest obj's underlying member method code with example usage: obj.testDel() without return types