code: def learn_one(self, x, y):
      # Convert {False, True} to {-1, 1}
      y = int(y)
      y_vw = 2 * y - 1
  
      ex = self._format_x(x)
      ex = f"{y_vw} | {ex}"
      self.vw.learn(ex)
  
file_path: river/benchmarks/model_adapters/vw.py
imports: from __future__ import annotations
  from vowpalwabbit import pyvw
  from river import base
label_desc: Use image node_id 1 for calling the VW2RiverClassifier obj's underlying member method code with example usage: obj.learn_one(x, y) without return types