docstr: Update the metric at each step along the horizon.
  
  Parameters
  ----------
  y_true
      Ground truth values at each time step of the horizon.
  y_pred
      Predicted values at each time step of the horizon.
docstr_tok: ["Update","the","metric","at","each","step","along","the","horizon",".","Parameters","--","--","--","--","--","y_true","Ground","truth","values","at","each","time","step","of","the","horizon",".","y_pred","Predicted","values","at","each","time","step","of","the","horizon","."]
code: def update(
      self, y_true: list[Number], y_pred: list[Number]
  ) -> ForecastingMetric:
      """Update the metric at each step along the horizon.
  
      Parameters
      ----------
      y_true
          Ground truth values at each time step of the horizon.
      y_pred
          Predicted values at each time step of the horizon.
  
      """
  
imports: from __future__ import annotations
  import abc
  import typing
  from numbers import Number
  from river import base, metrics
label_desc: Use image node_id 1 for calling the ForecastingMetric obj's underlying member method code with example usage: obj.update(y_true, y_pred) without return types