input: Write a function to predict the next day's forecast temperature using the exponential smoothing algorithm given the past three day's forecast temperatures. The function should return the predicted temperature. If the input list is empty, the function should return 0.
  def predict_temperature(temperature_list):
      if not temperature_list:
          return 0
      alpha = 0.5 # Confidence value
      predicted_temperature = temperature_list[-1] # Initializing prediction
      for temperature in temperature_list[:-1]:
          predicted_temperature = alpha*temperature + (1-alpha)*predicted_temperature
      return predicted_temperature
  
  assert predict_temperature([21, 22, 20]) == 20.5
  assert predict_temperature([15, 14, 13]) == 13.5
  assert predict_temperature([]) == 0
  assert predict_temperature([30, 28, 29]) == 28.5
output: def predict_temperature(temperature_list):
      if not temperature_list:
          return 0
      alpha = 0.5
      predicted_temperature = temperature_list[-1]
      for temperature in temperature_list[:-1]:
          predicted_temperature = alpha*temperature + (1-alpha)*predicted_temperature
      return predicted_temperature