class_docstr: Symmetric mean absolute percentage error.
  
  Examples
  --------
  
  >>> from river import metrics
  
  >>> y_true = [0, 0.07533, 0.07533, 0.07533, 0.07533, 0.07533, 0.07533, 0.0672, 0.0672]
  >>> y_pred = [0, 0.102, 0.107, 0.047, 0.1, 0.032, 0.047, 0.108, 0.089]
  
  >>> metric = metrics.SMAPE()
  >>> for yt, yp in zip(y_true, y_pred):
  ...     metric.update(yt, yp)
  
  >>> metric
  SMAPE: 37.869392
code: def get(self):
      return 100 * super().get()
  
imports: from __future__ import annotations
  from river import metrics
label_desc: Use image node_id 2 for calling the SMAPE obj's underlying member method code with example usage: obj.get() and returns: unknown