Python字符串删除特定字符出现3次后的所有内容

def remove_chars(string, target):
    char_count = {}
    result = ""

    for char in string:
        char_count[char] = char_count.get(char, 0) + 1
        if char_count[char] <= 3:
            result += char

    return result

input_string = "Hello, world! This is a test string."
target_char = "l"

output_string = remove_chars(input_string, target_char)
print(output_string)