ظهور الخطأ التالي TypeError: 'int' object is not iterable أثناء محاولة تدريب شبكة عصبية

أقوم بتدريب شبكة عصبونية للتعرف على الأرقام mnist ولكنها لا تعمل على google colab

import numpy as np
import pandas as pd
from keras.models import Sequential
from keras.layers import Dense , Activation, Dropout
from keras.models import Sequential
from keras.utils.np_utils import to_categorical
from keras.datasets import mnist
(x_train, y_train),(x_vaild, y_vaild) = mnist.load_data()
y_train = to_categorical(y_train)
y_vaild = to_categorical(y_vaild)
image_size = x_train.shape[1]
input_size = image_size * image_size
x_train = np.reshape(x_train, [-1, input_size])
x_train = x_train.astype('float32') / 255
x_test = np.reshape(x_test, [-1, input_size])
x_test = x_test.astype('float32') / 255
batch_size = 32
hidden_units = 256
model = Sequential()
model.add(Dense(hidden_units, input_dim=input_size))
model.add(Activation('relu'))
model.add(Dropout(0,45))
model.add(Dense(hidden_units))
model.add(Activation('relu'))
model.add(Dropout(0,45))
model.add(Dense(10))
model.add(Activation('softmax'))
model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
model.fit(x_train, y_train, epochs=5,validation_data=[x_vaild, y_vaild], batch_size=batch_size))
---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-10-51503a456d4c> in <module>()
     34 model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
     35 
---> 36 model.fit(x_train, y_train, epochs=5,validation_data=[x_vaild, y_vaild], batch_size=batch_size)

9 frames

/usr/local/lib/python3.7/dist-packages/tensorflow/python/framework/func_graph.py in wrapper(*args, kwargs)
    984           except Exception as e:  # pylint:disable=broad-except
    985             if hasattr(e, "ag_error_metadata"):
--> 986               raise e.ag_error_metadata.to_exception(e)
    987             else:
    988               raise

TypeError: in user code:

    /usr/local/lib/python3.7/dist-packages/keras/engine/training.py:830 train_function  *
        return step_function(self, iterator)
    /usr/local/lib/python3.7/dist-packages/keras/engine/training.py:813 run_step  *
        outputs = model.train_step(data)
    /usr/local/lib/python3.7/dist-packages/keras/engine/training.py:770 train_step  *
        y_pred = self(x, training=True)
    /usr/local/lib/python3.7/dist-packages/keras/engine/base_layer.py:1006 __call__  *
        outputs = call_fn(inputs, *args, **kwargs)
    /usr/local/lib/python3.7/dist-packages/keras/engine/sequential.py:375 call  *
        return super(Sequential, self).call(inputs, training=training, mask=mask)
    /usr/local/lib/python3.7/dist-packages/keras/engine/functional.py:416 call  *
        inputs, training=training, mask=mask)
    /usr/local/lib/python3.7/dist-packages/keras/engine/functional.py:551 _run_internal_graph  *
        outputs = node.layer(*args, **kwargs)
    /usr/local/lib/python3.7/dist-packages/keras/engine/base_layer.py:1006 __call__  *
        outputs = call_fn(inputs, *args, **kwargs)
    /usr/local/lib/python3.7/dist-packages/keras/layers/core.py:205 dropped_inputs  *
        inputs,
    /usr/local/lib/python3.7/dist-packages/keras/utils/control_flow_util.py:107 smart_cond  *
        pred, true_fn=true_fn, false_fn=false_fn, name=name)
    /usr/local/lib/python3.7/dist-packages/keras/layers/core.py:195 _get_noise_shape  *
        for i, value in enumerate(self.noise_shape):
    /usr/local/lib/python3.7/dist-packages/tensorflow/python/autograph/operators/py_builtins.py:400 enumerate_  
        return _py_enumerate(s, start)
    /usr/local/lib/python3.7/dist-packages/tensorflow/python/autograph/operators/py_builtins.py:408 _py_enumerate
        return enumerate(s, start)

    TypeError: 'int' object is not iterable