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Using "is" for anything but singleton can increase costs

Count one violation each time one of the operand of is (or is not) is not None, True or False.

Why you should care

Testing the identity of two objects can be achieved in python with a special operator called is. Most prominently it is used to check whether an variable points to None. But the operator can examine any kind of identity. This often leads to confusion because equality of two different objects will return False . forgiveness : As some exception can be tolerated, a few percentage of "is" for checking identity of two objects other than singleton should be allowed in the model.

Business Impacts

It is recommended to avoid these in order to ensure the code is more readable and cost effective.

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CAST recommendations

References

https://www.quantifiedcode.com/knowledge-base/readability/%60not%20...%20is%60%20used%20instead%20of%20%60is%20not%60/4ORGpHyx

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For reference only. For the complete details please refer the original article
https://doc.casthighlight.com/alt_instanceof-avoid-using-is-for-anything-else-than-singleton/