input: Write a function to generate a Machine Learning model in Python that can recognize handwritten digits from 0 to 9. The function should load the MNIST dataset, define a neural network model with specified layers, preprocess the data, and fit the model. The function should return the trained model.
  assert (generate_digit_recognition_model()).predict(X_test).shape==(10000, 10)
  assert (generate_digit_recognition_model()).predict(X_train).shape==(60000, 10)
output: def generate_digit_recognition_model():
      from tensorflow.keras.datasets import mnist
      from tensorflow.keras.models import Sequential
      from tensorflow.keras.layers import Dense, Flatten
      from tensorflow.keras.utils import to_categorical
  
      (X_train, y_train), (X_test, y_test) = mnist.load_data()
      X_train = X_train.reshape(-1, 28*28) / 255.0
      X_test = X_test.reshape(-1, 28*28) / 255.0
      y_train = to_categorical(y_train, 10)
      y_test = to_categorical(y_test, 10)
  
      model = Sequential([
          Flatten(input_shape=(28*28,)),
          Dense(128, activation='relu'),
          Dense(64, activation='relu'),
          Dense(10, activation='softmax')
      ])
  
      model.compile(optimizer='adam', loss='categorical_crossentropy', metrics=['accuracy'])
      model.fit(X_train, y_train, epochs=5, batch_size=32, validation_data=(X_test, y_test))
      
      return model