[4, 10, 20, 12]
实现一个函数，返回给定列表中最高的数值
def maxValue(array):
    maxVal = 0
    for i in array:
        if i > maxVal:
            maxVal = i 
    return maxVal 

maxVal = maxValue([4, 10, 20, 12]) 
print(maxVal)