epequeno/ThinkPy-Solutions — comment on commit eebd4566f01500f54087d8157afa43b506228d79
File:  line 0
By epequeno:

Originally the code didn't produce errors because the definition used the global variables stringOne and stringTwo, even if they didn't match the strOne and strTwo used in naming the function. Had the string variables been named something else, it would have caused an error.