关于#python#的问题，请各位专家解答！

请问打对号怎么写？怎么调用这个函数？什么是断言语句？请大lao指教一下

from math import log
def func():
    x,y=input().split()
    try:
        x,y=float(x),float(y)
    except:
        print("输入错误")
        return
    # if 3*x-y+1<0:
    #     print("值小于0")
    #     return 
    # elif 3*x-y+1==0:
    #     return -float('inf')
    # else:
    #     return log(3*x-y+1)
    assert 3*x-y+1>0,"值不大于0"
    return log(3*x-y+1)
print(func())