input: 
  import numpy as np
  import tensorflow as tf
  
  def create_model():
      """ Create a neural network model using TensorFlow/Keras that takes a trajectory of stock prices
      and predicts the stock price for the next day.
      >>> create_model()
      <tensorflow.python.keras.engine.sequential.Sequential object at 0x...>
      """
      model = tf.keras.Sequential([
          tf.keras.layers.Dense(64, activation='relu', input_shape=(7, )),
          tf.keras.layers.Dense(1)
      ])
  
      model.compile(loss='mean_squared_error', 
                    optimizer='adam',
                    metrics=['accuracy'])
  
      return model
  
output:     return model