code: def __call__(self, y: float) -> float:
      a = self._a
      b = self._b
      c = self._c
      return (
          a
          + min(0, np.floor(y - b)) * a * (b - y) / b
          - min(0, np.floor(c - y)) * (1.0 - a) * (y - c) / (1.0 - c)
      )
  
imports: from __future__ import annotations
  import abc
  from typing import Callable
  from typing import Union
  import numpy
label_desc: Use image node_id 2 for calling the FlatRegionBiasTransformation obj's underlying member method code with example usage: obj.__call__(y) and returns: unknown