Python 3: How to reflect if a raw- or normal string was used?

I have a configuration file where users can provide regular expressions to match against words, e.g.

wordlist =  ["is", r"\b(and)\b"]

The problem is: if a user provides "is", this will also match against "This" -- which is not what I want. The second regex is better since it uses word-boundaries. Unfortunately, this is annoying to do for each word.

My idea is the following: let the user specify raw-strings (which are taken untouched for regex-matching) and "normal strings" (which are first translated to r"\b({})\b".format(word) for convenience). Is there a way to implement this? Can reflection be used to tell if a string was initially provided as raw-string?