Tensorflow #tf.function: AttributeError: in converted code - python-3.x

Question

I created a class and defined the train_step function inside it: TF tutorial: NMT_attention
Without using the #tf.function significantly increases the training time. On defining it, I get a conversion error for the private variables declared inside the class.
#tf.function
def train_step(self, input, target, encoderHidden):
loss = 0
with tf.GradientTape() as tape:
encoderOutput, encoderHidden = self.__encoder(input, encoderHidden) #throws error
Below is the traceback:
Using TensorFlow backend.
2019-09-20 12:54:32.676302: I tensorflow/core/platform/cpu_feature_guard.cc:142] Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX2 FMA
Traceback (most recent call last):
File "/Users/Users/Library/Python/lib/python/site-packages/proj/Models/attention_model.py", line 499, in <module>
model.fit(path, epochs)
File "/Users/Users/Library/Python/lib/python/site-packages/proj/Models/attention_model.py", line 383, in fit
loss = self.train_step(input, target, encoderHidden)
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/eager/def_function.py", line 416, in __call__
self._initialize(args, kwds, add_initializers_to=initializer_map)
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/eager/def_function.py", line 359, in _initialize
*args, **kwds))
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/eager/function.py", line 1360, in _get_concrete_function_internal_garbage_collected
graph_function, _, _ = self._maybe_define_function(args, kwargs)
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/eager/function.py", line 1648, in _maybe_define_function
graph_function = self._create_graph_function(args, kwargs)
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/eager/function.py", line 1541, in _create_graph_function
capture_by_value=self._capture_by_value),
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/framework/func_graph.py", line 716, in func_graph_from_py_func
func_outputs = python_func(*func_args, **func_kwargs)
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/eager/def_function.py", line 309, in wrapped_fn
return weak_wrapped_fn().__wrapped__(*args, **kwds)
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/eager/function.py", line 2155, in bound_method_wrapper
return wrapped_fn(*args, **kwargs)
File "/Users/Users/work_env/lib/python3.7/site-packages/tensorflow/python/framework/func_graph.py", line 706, in wrapper
raise e.ag_error_metadata.to_exception(type(e))
AttributeError: in converted code:
relative to /Users/Users:
Library/Python/lib/python/site-packages/proj/Models/attention_model.py:262 train_step *
encoderOutput, encoderHidden = self.__encoder(input, encoderHidden)
work_env/lib/python3.7/site-packages/tensorflow/python/autograph/impl/api.py:329 converted_call
f = getattr(owner, f)
AttributeError: 'Model' object has no attribute '__encoder'