code: def beginning_of_line(event):
      "Move to the start of the current line."
      buff = event.current_buffer
      buff.cursor_position += buff.document.get_start_of_line_position(
          after_whitespace=False
      )
  
imports: from __future__ import unicode_literals
  from prompt_toolkit.enums import IncrementalSearchDirection, SEARCH_BUFFER
  from prompt_toolkit.selection import PasteMode
  from six.moves import range
  import six
  from .completion import generate_completions, display_completions_like_readline
  from prompt_toolkit.document import Document
  from prompt_toolkit.enums import EditingMode
  from prompt_toolkit.key_binding.input_processor import KeyPress
  from prompt_toolkit.keys import Keys
label_desc: Use image node_id 3 for calling a global function with example usage: beginning_of_line(event) without return types