code: def test_mode_F():
      src = hopper("L")
      data = list(src.getdata())
      im = Image.new("F", src.size, 0)
      im.putdata(data, 2.0, 256.0)
  
      target = [2.0 * float(elt) + 256.0 for elt in data]
      assert list(im.getdata()) == target
  
file_path: pillow/Tests/test_image_putdata.py
imports: from __future__ import annotations
  import sys
  from array import array
  import pytest
  from PIL import Image
  from .helper import assert_image_equal, hopper
label_desc: Use image node_id 6 for calling a global function with example usage: test_mode_F() without return types