Python -检查字符串中嵌入了多少个字符串实例

def count_instances(target_str, instance_str):
    count = target_str.count(instance_str)
    return count

target_str = "This is a test string. It contains multiple instances of the word test."
instance_str = "test"

result = count_instances(target_str, instance_str)
print("The target string contains", result, "instances of the word", instance_str)

The target string contains 2 instances of the word test