将字符串解析为具有两个键和一个值的字典

def parse_string_to_dict(string):
    # 去除字符串两端的空格
    string = string.strip()
    
    # 检查字符串格式是否正确
    if string[0] != "{" or string[-1] != "}":
        return None
    
    # 去除字符串的大括号
    string = string[1:-1]
    
    # 按逗号分割字符串
    parts = string.split(",")
    
    # 检查字符串是否包含两个键值对
    if len(parts) != 2:
        return None
    
    # 解析键值对
    key1, value1 = parts[0].split(":")
    key2, value2 = parts[1].split(":")
    
    # 去除键和值两端的空格
    key1 = key1.strip()
    value1 = value1.strip()
    key2 = key2.strip()
    value2 = value2.strip()
    
    # 构建字典
    result = {
        key1: value1,
        key2: value2
    }
    
    return result