如何在tkinter canvas中更改文本对象中间单个单词的颜色？

import tkinter as tk

root = tk.Tk()
canvas = tk.Canvas(root, width=400, height=400)
canvas.pack()

text = canvas.create_text(200, 200, text="Hello World", font=("Arial", 20))

import re

def change_color(event):
    canvas.itemconfig("word", fill="red")

def change_word_color(word):
    matches = re.finditer(r'\b%s\b' % word, canvas.itemcget(text, "text"))
    for match in matches:
        start = match.start()
        end = match.end()
        canvas.itemconfig(text, tag=[("word", "%d.%d" % (start, end))])

canvas.tag_bind("word", "<Button-1>", change_color)
change_word_color("Hello")