理解Python的with as语句

简单的说，

with open(filepath, 'wb') as file:

　　file.write("something")

等价于：

file = open(filepath)

try:

　　file.write("something", 'wb')

finally:

　　file.close()

总的来说with... as包含一个错误处理和一个文件关闭功能！