如何检查双精度变量开头的小数？

import re

def check_double_variable(decimal):
    decimal_str = str(decimal)
    pattern = r'^\d*\.\d+'
    match = re.match(pattern, decimal_str)
    if match:
        return True
    else:
        return False

# 示例用法
double_var = 0.123456789
if check_double_variable(double_var):
    print("双精度变量开头为小数")
else:
    print("双精度变量开头不是小数")