code: def scroll_half_page_down(event):
      """
      Same as ControlF, but only scroll half a page.
      """
      scroll_forward(event, half=True)
  
file_path: catboost/contrib/python/prompt-toolkit/py2/prompt_toolkit/key_binding/bindings/scroll.py
imports: from __future__ import unicode_literals
  from prompt_toolkit.layout.utils import find_window_for_buffer_name
  from six.moves import range
label_desc: Use image node_id 4 for calling a global function with example usage: scroll_half_page_down(event) without return types