Implementation of the parameterization decorators.

  Args:
    naming_type: The naming type.
    testcases: Testcase parameters.

  Returns:
    A function for modifying the decorated object.

def _ParameterDecorator(naming_type, testcases):
  """Implementation of the parameterization decorators.

  Args:
    naming_type: The naming type.
    testcases: Testcase parameters.

  Returns:
    A function for modifying the decorated object.
  """
  def _Apply(obj):
    if isinstance(obj, type):
      _ModifyClass(
          obj,
          list(testcases) if not isinstance(testcases, collections.Sequence)
          else testcases,
          naming_type)
      return obj
    else:
      return _ParameterizedTestIter(obj, testcases, naming_type)

  if _IsSingletonList(testcases):
    assert _NonStringIterable(testcases[0]), (
        'Single parameter argument must be a non-string iterable')
    testcases = testcases[0]

  return _Apply