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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get(self, key):
 """Gets a value by a key. Args: key (str):
 Key to retrieve the value. Returns: Retrieved value. """

    self._create_file_if_none_exists()
    with open(self.filename, 'rb') as file_object:
      cache_pickle = pickle.load(file_object)
      val = cache_pickle.get(key, None)
      return val