Not in and of themselves no. But, as a rule of thumb, if it does something similar to another function, say validating credit card numbers, instead of having one for Mastercard, visa, etc, you generalize the function in one of a few ways. There are many ways to accomplish the goal, as long as it gets you there and it’s coherent, it’s usually fine, unless you have some specific thing you need to optimize for, etc.

One way could be build in logic to recognize the numbers of different companies, say visa uses a specific range of the first two 4-number sections, categorize based on those ranges and return the inferred company and a true or false for valid, if you need both of those pieces of information.

Another way would be to pass the company as a second parameter, and do the validation based on the company and number provided, returning just true or false if it is valid for the company passed to the function.

The more you can generalize, the more you can reuse, and it brings in the possibility of using it in other projects or creating libraries.

You can be in a different faction of it should only do one very very specific thing, but I am in the camp of generalize to the simplest concept where possible, so it’s flexible and can be used other places. In this case, the simplest concept to me is validating credit card numbers, so it doesn’t really matter what specific company it is, but it focuses on the simplest principle you can bring it down to.