code: def test_def_statement(self):
      # empty def
      self._assert_highlighting("def", {"KEYWORD": [("1.0", "1.3")]})
  
      # def followed by identifier
      self._assert_highlighting(
          "def foo:",
          {"KEYWORD": [("1.0", "1.3")], "DEFINITION": [("1.4", "1.7")]},
      )
  
      # def followed by partial identifier
      self._assert_highlighting(
          "def fo",
          {"KEYWORD": [("1.0", "1.3")], "DEFINITION": [("1.4", "1.6")]},
      )
  
      # def followed by non-keyword
      self._assert_highlighting("def ++", {"KEYWORD": [("1.0", "1.3")]})
  
imports: from idlelib import colorizer
  from test.support import requires
  import unittest
  from unittest import mock
  from idlelib.idle_test.tkinter_testing_utils import run_in_tk_mainloop
  from functools import partial
  import textwrap
  from tkinter import Tk, Text
  from idlelib import config
  from idlelib.percolator import Percolator
label_desc: Use image node_id 15 for calling the ColorDelegatorTest obj's underlying member method code with example usage: obj.test_def_statement() without return types