python设计程序 寻找字符

】寻找字符串"I think hope is a good thing."中字符串"hope"的下标,并将字符串中的hope替换成freedom,将新字符串保存到变量result中并在屏幕上输出。（使用replace方法）

str = "I think hope is a good thing."
print(str.find("hope"))

result = str.replace("hope","freedom")
print(result)