code: def horizoned_smape(y, yhat):
      """Return the symmetric mean absolute percentage error over all horizons.
  
      Args:
        y: An array containing the true values.
        yhat: An array containing the predicted values.
  
      Returns:
        A list a, with a[i] containing the SMAPE over yhat[0] ... yhat[i].
      """
      return [
          smape(y[: i + 1], yhat[: i + 1]) for i in range(len(yhat))
      ]
  
imports: import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: horizoned_smape(y, yhat) and returns: unknown