code: def backward_delete_char(event):
      "Delete the character behind the cursor."
      if event.arg < 0:
          # When a negative argument has been given, this should delete in front
          # of the cursor.
          deleted = event.current_buffer.delete(count=-event.arg)
      else:
          deleted = event.current_buffer.delete_before_cursor(
              count=event.arg
          )
  
      if not deleted:
          event.cli.output.bell()
  
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 19 for calling a global function with example usage: backward_delete_char(event) without return types