if file exists, adds an '_1' to filename. If '_x' (where x is a number) exists, then it increments x. Intelligent renaming of filepaths?

change_filepath_if_exists

    def change_filepath_if_exists(filepath):
        f, ext = os.path.splitext(filepath)

        if os.path.exists(filepath):

            if f[f.rfind('_')+1:].isdigit():
                oldnum = f[f.rfind('_')+1:]
                newnum = str(int(oldnum)+1)
                newf = f[0:-len(oldnum)] + newnum
                f = newf
                print('1')
            else:
                f = f + '_1'
                print('2')
                print(f)
            return change_filepath_if_exists(f+ext)
        else:
            return f+ext