input:     def predict_temperature(temperature_list):
          """ Uses the exponential smoothing algorithm to predict the next day's forecasted temperature 
          given the past three day's forecasted temperatures.
          >>> predict_temperature([21, 22, 20])
          20.5
          """
          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
output:     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