Where is the no-ex-assign coming from?

[GarfieldDeepClone]

Hi :)

I'm just curious and like to know where the 'no-ex-assign' rule name is defined? I can't find it anywhere. I just see the noExAssignRule.js file.

And why do I have to define the rule when I extended tslint-eslint-rules?
I don't understand how the extends of tslint-eslint-rules work. I'm used to the case that in the extended node_modules directory are some js files which export rules. But I can't see such one in tslint-eslint-rules