如何通过每次删除4个字符来获得字符串的所有组合？

def get_combinations(string, current_combination, result):
    if len(current_combination) == 4:
        result.append(current_combination)
        return
    
    for i in range(len(string)):
        char = string[i]
        new_string = string[:i] + string[i+1:]
        new_combination = current_combination + char
        get_combinations(new_string, new_combination, result)

def get_all_combinations(string):
    result = []
    get_combinations(string, "", result)
    return result

# 示例调用
string = "abcdefgh"
combinations = get_all_combinations(string)
print(combinations)