def _ascii_title(data, res):
    """ Does .title() on an ASCII string """
    previous_is_cased = False
    for idx in range(len(data)):
        code_point = _get_code_point(data, idx)
        if _Py_ISLOWER(code_point):
            if not previous_is_cased:
                code_point = _Py_TOUPPER(code_point)
            previous_is_cased = True
        elif _Py_ISUPPER(code_point):
            if previous_is_cased:
                code_point = _Py_TOLOWER(code_point)
            previous_is_cased = True
        else:
            previous_is_cased = False
        _set_code_point(res, idx, code_point)
 Does .title() on an ASCII string 
numba/cpython/unicode.py