python 等比数列

def is_geometric(li):
    if len(li) <= :
        return True
    # Calculate ratio
    ratio = li[]/float(li[])
    # Check the ratio of the remaining
    for i in range(, len(li)):
        if li[i]/float(li[i-]) != ratio:
            return False
    return True   

print(is_geometric([, , , ]))  

print(is_geometric([, , 2.5, 1.25]))  

print(is_geometric([, , , ]))