code: def repr_split(self):
      return f"x < {self.threshold}"
  
file_path: river/river/tree/test_base.py
imports: from __future__ import annotations
  from river.tree.base import Branch, Leaf
label_desc: Use image node_id 4 for calling the BinaryBranch obj's underlying member method code with example usage: obj.repr_split() and returns: str, self