python is 2.7

For example, like this: from defs import raiseApiEx as err
This line is directly gray. When err is used below, it is directly marked with a wavy line prompt.

There was no such thing in eclipse before. I heard that the syntax detection in pychram is relatively strict.
But isn't from defs import raiseApiEx as err supported by syntax?
What regulations are violated? Although it does not affect the operation, I would like to know why it is prompted.